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Author Topic: Building a Dumas Chris Craft Runabout kit  (Read 26576 times)

SailorGreg

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Building a Dumas Chris Craft Runabout kit
« on: January 25, 2014, 10:22:02 PM »

I recently purchased this kit from a fellow Mayhemer (thanks Mark) who had decided he was never going to get around to putting it together.  It is a few years old, and I don’t know how it compares with the kit you buy today, so some of my comments as we go through the build might not apply to a modern kit. (But of course they might!)

I plan to build this pretty much out of the box, although there are a few mods I hope to make as I go along.  I have read a lot of build threads elsewhere of this type of boat, although they are few and far between here on MBM.  My only previous significant model boat building has been my steam launch (http://www.modelboatmayhem.co.uk/forum/index.php/topic,41151.0.html) and I have never built a model boat kit before, so this is going to be an interesting ride.  If there is anyone out there who has experience of Dumas kits, please feel free to chip in.  O0

Having sorted through the box of bits (all present and correct), the first step is to produce a building board.  Mine is from 20mm MDF and is marked out as instructed in the Dumas instructions.



Well, that was easy.  Next is separating the diecut frame and keel parts from the plywood sheets.  I have to say I have seen better quality ply in my time, and I picked up a few splinters during this process (including one down a finger nail – ouch!   >:-o )  Other than that the pieces came out pretty easily with a sharp scalpel, although at this stage some are pretty fragile as I found out.  Still, nothing a drop of CA can’t fix.



I also came across a potential issue with the frames.  I put two marks on each of the frame position lines to allow me to get the frame central (something the Dumas instructions don’t suggest) and then found when I put the frames to these marks that the keel slot was off-centre.



You can see that the corners of the frame are on the pencil marks each side but the centre line is not in the centre of the slot.  All the frames that slot on to the keel had a similar offset.  The keel was also a loose fit in the slot, so some of the apparent offset could be lost by pushing the keel to one side of the slot.  After thinking about this, I decided to press on and align the keel and frames as best I could within my marks and trust that the hull fairing would even out any discrepancies.  I should point out to those unfamiliar with Dumas kits that the central keel only covers the forward half of thr boat.  The rear half centreline is defined by a "butterfly keel" which is basically two flat strips of wood fixed over the aft frames.  The keel you see in the next few pictures is only half the length of the finished boat.  All will become clear later!  :-))

The keel is a double thickness of ply.  I glued the port and starboard halves of the keel together with a simple jig to make sure the edges were exactly aligned as I clamped the two halves together – just a few strips CA’ed onto a firm base.



At the next stage of erecting the keel and first 6 frames I did favour getting the keel along the centre line over getting the frames exactly centred.  It remains to be seen if I regret this in the future! Actually once the frames and keel were glued together and to the building board, there didn’t seem to be any huge discrepancies (but then I don’t know at this stage what is significant and what isn’t!  :embarrassed:



Well, that’s it for the moment.  I am already a little more advanced than this, so the next few posts will catch up to where I am.  I've just realised I haven't posted any piccies of the kit contents, which seems to be a favoured starting point.  I'll see what I can do on that front for the next post.

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #1 on: January 25, 2014, 10:53:40 PM »

Hello Greg,
 
Those frames look awfully fragile at the moment, should become more rigid as you progress though and things tighten up.
Never built one of those myself but still find it an interesting subject O0
 
Looking forward to your progress :-))
 
Regards,
 
Ray.
 
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #2 on: January 25, 2014, 11:27:11 PM »


Nice start Greg!   :-))
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #3 on: January 26, 2014, 12:50:28 PM »

I recently purchased this kit from a fellow Mayhemer (thanks Mark) who had decided he was never going to get around to putting it together.

Good luck with it Greg - I've too many projects and I'll be interested to see the progress.

Thoroughly enjoyed your steam launch build - I've been inspired to get on with my MHB Topaz...

Mark
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SailorGreg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #4 on: January 28, 2014, 09:55:47 PM »

First, as promised, a couple of piccies of the box and its contents. 





At the top are the vacuum moulded seats – I will probably use these initially but I rather fancy some vinyl (or even real leather) ones, so will keep copies of all the cockpit pieces to allow me to make replacements sometime later.  Under these is a bundle of mahogany planks which will form the outer planking of the hull and deck.  The cardboard tube contains styrene strips which will be the caulking between the deck planks.  Under the tube are some mahogany sheets for sheer planks and other trim pieces.  In the box proper are other wood sheets, mainly birch ply, to build the internal structure.  By the time I took the photo the sheets of nasty ply for the frames had already gone to be used.  The small box on the left contains a piece of plastic for the windscreen, the rudder, propeller, dowel for flagstaffs and a few other bits and bobs.  A prop shaft is also provided but I plan to fit a replacement with a metric thread (as I also plan to replace the propeller).  In the middle is a plastic bag of chromed fittings.  These are of rather average quality and I suspect will be the cause of great indecision when the time comes to fit them – use, modify or replace?  On the right are the “decorations” – name, home port and self adhesive flags

OK, on to the real business.  The next step is to erect the rest of the frames along with the sheers and chines, which lock everything together.  All these parts have to be slotted together and put in place before anything is glued, so having a third (and fourth) hand is a distinct advantage.   O0 Unfortunately I am not so blessed, so I just cursed, swore, picked everything of the floor a few times, and eventually got to this stage.



All the joints now get a drop of CA and a squirt of kicker, as do the legs of the frames where they rest on the building board.  Everything then becomes a lot more solid.  :-))

Next come some stringers and for some reason those supplied were a little short.



You can see the cutout in frame 2 where the stringers should reach, but they don’t.   :o   Not to worry, I made up replacements from some Douglas fir I had and pressed on.  Next problem – one of my replacements was too short but I didn’t find out until I had started gluing it in place.  :embarrassed: (The first person to say “measure twice, cut once” can leave now!)  Rather than rip out the glued joints, which I thought might damage the fragile frames, I CA-tacked a second piece of wood alongside the stringer, tacked this to a large block which I braced against the frames then planed a scarph joint in situ.  I popped the two pieces apart, turned one round and glued them together – instant longer stringer!  Here’s the joint being cut.



Having got over that little wrinkle, the other bits and pieces needed before planking begins were added.  The next picture shows the curved transom piece and the end of the “butterfly keel”.



and then the balsa blocks that form the bow.  Here they are with shaping underway  -



and finished –



Next was a bit of fairing and I made up a board for the larger, flatter areas (80 grit as you can see).



I made sure all edges had been touched with the abrasive and that the bevel formed along the edge of the chine was even all around, then stopped.   Next was the first planks, and here they are.



Next time will be the first layer of planking and separating from the building board,  Can’t wait to see her right way up!

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #5 on: February 03, 2014, 09:59:58 PM »

The first layer of planking all went fairly smoothly, although there were one or two points where I had to stop and ponder, and a few adjustments to the frames were made as I’ll explain as we go along.  Starting on the flat stern area is great because it is all easy there, and things roll along pretty quickly.  Just one short session gets me here -



As I was using kicker on the CA I found I did need to clean the glue away from each joint – the corner of a steel rule worked pretty well as a scraper.



(Yes, I know it’s not the right tool but it works!  :embarrassed: )

Although I tried to keep the centre join central, I did wander off at one point so corrected myself –



Not sure if that will really matter once the fairing is done, but it keeps me happy.  Sorry for the blurred picture.

One area where the instructions are silent and I slowed down for a long think is the point near the bow where the chine washes out into the bow profile - how should I join the two runs of planking?  Along the main part of the hull there is a simple overlap joint at something close to right angles. 



At the bow, the two runs of planking have to form a butt joint.  This is how I made the transition, although those with more experience than me might be able to offer better ways. 







I hope the pictures are self-explanatory.  However, this is getting a little ahead of things.  After I had completed the bottom planking and planed it flush with the chines I tried measuring the frames from the centre line to make sure everything was going to turn out symmetrical.  This proved very tricky so I built myself a jig to slide along the building board to allow me to check offsets from the centreline at each frame. 



The jig runs on two short lengths of brass angle and the building board does need to be parallel-sided for this to work.  I measured the hull each side from the inside faces of the uprights, and these obviously need to be identical distances from the centreline of the building board and hull.  I spent some time making sure this was the case (and shimming one side because my centreline wasn’t exactly in the centre of the board) but after that I could take measurements from each side with confidence.  Mostly the hull was symmetrical give or take a shaving or two with the plane.  There were two areas that seemed noticeably wrong.  Firstly at the transom where the ends of the sheers were about 3mm different (probably because I wasn’t careful enough when I glued them in place as the interlocking slots were pretty sloppy here), and around frames 4 and 5 where the two sides were noticeably different.  I wasn’t sure whether to sand away one side or add material to the other to make them the same.  The “fuller” side did seem fair when I viewed it and ran battens along it, so I eventually decided to add some material to the “thinner” side.



I added thin strips to frames 4 and 5 and a piece to the stringer, then faired everything in until the measurements were the same port and starboard.  I then pressed on with the planking.  I found the stern area to be quite tricky this time, and eventually decided to leave the triangular area at the transom (that’s the area just above the pencil in the picture below) until I had the hull the right way up, when I will also fix the sheer measurements.



Once I had all the planking in place, I faired the hull with my fairing board, a small palm sander and a little help from a friend… %)



I found it very helpful to scribble lightly all over the surface when fairing so I could see where I still needed to work.  I renewed the scribbling several times as I did this and with a small amount of filling as well I ended up with a hull that looked and felt smooth, and was beginning to show some of the elegance of the finished boat –



Once I was happy with the fairing I cut the hull off the building board and turned it over – first view of the inside -



Oh I do like that herring bone pattern  :-)) :-))   This is pretty well where I am now, so things might slow down a little from here on.  Really enjoying this build!

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #6 on: February 03, 2014, 10:17:22 PM »

I am following this thread with great interest Greg  :-)) ....but when did you borrow my roll of 100% premium quality Australian 8 ply cotton string?  >>:-( .....Derek 
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #7 on: February 03, 2014, 10:28:41 PM »

Been following this one as I keep looking at the CC cobra 27 kit from Dumas.


What's your opinion on the quality of the kit, wood etc?
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #8 on: February 04, 2014, 06:28:00 PM »

Your string Derek?   %) %)

Well, you are welcome to come and collect it in person!  (As you know I used it originally in  my steam boat build -



but it is amazing how often having a ball of string to hand comes in really useful!   O0 )

essex2visuvesi - I haven't really done any kit building since my last Airfix Spitfire in 19** (assuming you don't count my steam engine - see above) so I am not really qualified to compare this to any other kit.  Given that, I would say that if you are used to making things and can work to a reasonable level of precision then this should not pose too many problems.  As to the quality of the wood, the birch ply is fine and I think the mahogany is OK although I haven't used any of that yet. The plywood provided for the frames and carcase is, frankly, rubbish and splinters easily.  Here's what happens if you are a little careless -



I realise that all kits make some concessions to price. I guess that is why this wood is used, and it is certainly useable with care, just slightly annoying (and painful!) when the splinters fly.  The kit also contains a prop shaft which didn't impress, (it is really tight in its bearings and would need some serious bedding in to reduce the friction) and while it is really nice to have chromed metal fittings it would have been better if the moulding lines had been removed before chroming!  A price thing again I suppose.

If this sounds like I am dissatisfied with the kit, I am not.  I am really enjoying building it and the overall design goes together well.  Although this is my first (recent) kit, I do make things in wood and have a fairly well equipped workshop.  I would say that for anyone who has successfully completed a wood kit or two, this is well within their skill level (so far, at least  %) - not sure how difficult it gets from here!).

Hope that helps.

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #9 on: February 07, 2014, 01:32:21 PM »

Now that the hull is right way up, a stand seemed a good idea.



This is purely for holding the hull during the building – I will make something a little prettier once she’s finished  O0   

First job was to finish off the corner at the stern I had left when the hull was upside down.  I am glad I did it this way because I found this piece (the long untrimmed piece) a bit tricky.



I had to put a fair bit of twist into this before I attempted to glue it in place.  Fortunately the birch ply takes this very well, and after being a bit brutal with the piece (just grip each end and twist hard!) it fitted fairly well.  I then started trimming off the “feet” of the frames and the overhanging edges of the planking.  At this point I wished I had spent a little more time cutting the individual pieces to size rather than leaving all sorts of odd angles and lengths hanging over the edges.  Oh well, next time….   ;)   A razor saw, small plane and chisel got rid of most of the surplus and then everything was sanded flat.  I did find the chisel most useful as you can pare down almost flush without putting lots of strain on the glued joints.



All sanded flush now –



I did leave the extended keel right at the bow because this holds a small screw that is my string centreline for taking measurements (making sure this boat is symmetrical seems to have become something of an obsession with me  %% ).  I plan to hang on to this as long as I can so I can keep checking.

At this stage I epoxied the inside of the hull while everything was still open and accessible.  Builders of this sort of boat do seem very keen on thinning their epoxy.  Although I have used epoxy quite a lot on full size boats, including building one, I had never thinned it.  Indeed, at full scale this is discouraged as it can weaken the resin.  However, the body of opinion made me wonder if this was a trick I should follow.  I did a little experiment – I coated the starboard half of the hull in full strength epoxy and thinned (about 20% thinners) the epoxy for the port half.  After all, if it turned out horrible at least it's on the inside  %)   Fairly soon after I had done this, it was obvious that the thinned epoxy had soaked into the wood much more than the unthinned.  As I write it is all still wet, so I will have to wait until it’s all cured to see what my final verdict will be.  It will be interesting to see if the thinned epoxy cures faster, slower or the same as the unthinned.  Here’s the epoxied hull, although both sides look the same here!



Stay tuned for the next exciting episode!

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #10 on: February 11, 2014, 10:56:10 PM »

It occurred to me that some reading here might not have a clear idea of what the finished product should look like, so I took the liberty of pinching this picture from a build log elsewhere by a much more competent modeller than me -



I hope mine looks as good as that when it's done.  O0

A quick update on the epoxy.  Here is a shot of the unthinned coat –



and the thinned side –



The unthinned epoxy looks shiny and is “squeaky” if you rub a finger over it.  The thinned epoxy soaked well in leaving most of the surface still with the texture of the wood.  It is, however, waterproof (I’ve tested it! :-)) ).  My feeling is that I actually want something between the two.  The epoxy I am using (this) is already fairly thin compared to the standard West or similar “full scale” products, so I think some very moderate thinning will make it easy to work but not too prone to just run into the corners.

I have also been thinking about the cockpits.  The internal sides of the cockpits are just the “splintery” ply that the frames are made from.  I admit that I haven’t tried finishing this to see what it looks like with some epoxy and/or varnish, but I would rather like the inside to be as smart as the outside (assuming I manage a decent finish on the outside of course  {-) ).  I had a small sheet of mahogany veneer that has been lying around for years, so I used this to cover the internal faces. 



I didn’t have quite enough to do all the exposed areas, but I will fill in the gaps with some of the waste from the die-cut sheets after pushing that through the thickness sander.  I also feel that the cockpits in the standard kit look a little bare and would prefer them to have some details to draw the eye.  I’m not sure whether all these boats were identical or whether there was some customisation at or after build.  But I’m not recreating a specific boat, so I think I’m allowed to have it like I want   O0 O0 O0 .  As a start I cut some storage holes in the rear cockpit sides. These will be backed with shallow boxes, although I haven’t yet decided how to finish the inside of these.  I realised that these boxes would stop me sliding the whole cockpit side piece into place (it slips in vertically) and I will have to separate the veneered section in the picture below from the side coaming piece.  Not a big drama though.  I am also thinking about some grab rails.  Anyone got any other ideas for furnishing the cockpits?



I am probably going to pause on the cockpit construction and deviate from the build sequence next.  I want to fit motor mounts that allow me to swap different motors in and out.  I plan to have bearers each side of the centreline with embedded machine screws on which a motor plate will sit and be fixed in place.  Each plate will be custom made for its motor, but I need to make sure that they all end up lined up with the prop shaft, so some careful measuring and fitting will be needed at this early stage.  I think that will be easier before any more structure goes into the hull.  I won’t fit any running gear permanently, but I will need to put it in place to make sure everything fits.  That should be my next job.

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #11 on: February 17, 2014, 09:29:57 PM »

A quick update on the motor mount.  As I said before I want to be able to swap motors reasonably easily so the basic mount needs to be adaptable.  My first step was to temporarily install the prop shaft.  I also put in a dummy rudder tube so I could make sure the propeller didn’t run into the rudder.  Since I didn't have my prop (I'm not using the Dumas one and have an M4 shaft) I used a disc of card to fill the space.



Inside it looked like this.



I should say straight away that in this and all the subsequent pictures the prop shaft is much longer than is needed, but having it long at this stage is actually an advantage because you can measure where it meets the motor position more easily.
At this point I made up a dummy engine to let me play around with angles and distances.  My prop shaft is 4mm and a 3/16” brass tube is a nice sliding fit over this.  My dummy engine is shown below.  The only critical things are to make sure the tube is fixed perpendicular to the wood block (I used a drill press to drill the hole) and the tube is centred in the motor mount – I scored the wood with a Forstner bit to mark a circle on its face which I could then centre in the mount’s opening.



Next step was to measure the shaft angle.  I stood a scrap of ply on the centreline and extended the line of the shaft by eye – took a few goes to get it just right, and the best way to check was to take a photo from inside the boat – I couldn’t get my fat head that far down!   :}



At this point I had a couple of false starts trying to design a versatile mounting system.  In the end I went for the straightforward solution – a flat bed with some mounting studs fixed in it.  I started with a blank of Douglas fir (because I had it handy)



I measured the athwartships angle of the hull bottom to the horizontal (is this the "deadrise" or is that a longitudinal measurement?   {:-{ ).  This is easy if you have one of these –



then transferred that angle (11 degrees in my case) to the front and rear faces of the blank.  A quick visit to the disc sander and the blank had a vee section that matched the inside of the hull.  Except it didn’t because the butterfly keel was in the way.  I didn’t really relish cutting out a channel to match this so I cheated and simple glued two keel offcuts to the edges.



That hole in the middle has no purpose whatsoever, it just happened to be in the piece of wood I picked up.   :D
Next I transferred the shaft angle from my ply scrap to the side of the blank.  I checked that the resulting motor shaft height would match the prop shaft and then cut and sanded the top of the blank down to the marked angle.  Four M4 bolts epoxied in from underneath and the motor base is finished.



This motor is about as big as you can fit in the space.  I also have a brushless that I plan to try, and am happy that I could fit anything smaller than this in with a baseplate made to fit the mounting studs.

I have a question relating to the fittings - the chrome finish on these is not the best, and I know others who have passed this way have taken the trouble to remove the chrome, properly finish and polish the fittings then re-chrome with a kit like this.  I'm not sure I am ready to go to those lengths, but has anyone tried this chrome paint, or anything similar?  If so, what is the verdict?  Convincing?  Durable?  I did get a can of Halfords chrome paint and found it disappointing - looked just like a silver paint to me, and the finish rubbed off very easily.  I'll probably post this question on the Paint section as well and see if Stavros wants to shout at me!   {-) {-)

Looks like other jobs are going to interfere with the boatbuilding for a few days,  :(( so it might be a while before the next episode appears – but I’ll be back!

Greg
 

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #12 on: March 01, 2014, 04:27:32 PM »

The Dumas kit provides a small container of mahogany stain and I wanted to have a play with this before committing to the boat itself.  I made up a section of deck planking for my experiments. I also bought some walnut stain to use on the king plank and margin planks.  I am not keen on the black-painted effect you can see in the picture of the finished boat a couple of posts back.  I felt that the walnut would be a little more subtle but still give the nice contrast.  I experimented on my dummy deck section and was quite pleased with the result - but didn't take a photo  :embarrassed: .

I then made up a mix of epoxy as I was going to coat the underside of the planking of the foredeck before fitting it.  I thinned the epoxy a little, put some on the planking then brushed a coat onto the deck section.  Here is the result.



 >:-o >:-o >:-o

Well that didn't go too well.  After taking the picture I grabbed the thinners and wiped it all off.  (I had the same effect on the decking material, but not to quite the same extent.  And nobody is going to see that anyway  :P

After letting the deck section dry off, and after a quick rub over with some fine wet'n'dry I coated it with unthinned epoxy -



 :-)) :-)) :-))

That's better.  Both stains are water based and were thoroughly dry when I put the epoxy on.  It looks like the surface was contaminated, but I'm not sure with what.  I will need to be careful when I do the real thing.

I am back on track with the Dumas instructions now after my little detour with the engine mount and epoxy trials.  The sides of the cockpits are fixed next – I had veneered these to match more closely with the final hull finish, and decided to score the veneer to represent planks.



I decided to do this after I had glued the rear cockpit sides in place, so had to do them in situ.  Fortunately the aft cockpit is exactly 6” long!  I scored either side of the steel rule which was just about the right spacing.



I moved on to planking the foredeck, which went pretty well until I got to the small triangles at the bow.  Nobody warned me that the last little pieces can fall straight through the hole into the sealed bow compartment never to be seen again!  >>:-( >>:-( Some support was needed, and if I had thought of this beforehand I would have glued a little shelf to the previous piece of decking to give that support to the final piece.  As it was I had to insert a piece with some double sided tape wrapped around a piece of wire.







It took me forever to catch the loose piece and extract it through the small hole.   %% That’ll teach me to think ahead.

When the deck was completed it was apparent that I hadn’t been nearly careful enough in getting everything faired nicely.  The deck was rather uneven and I was resigned to a fair bit of filling and sanding.  There was also a distinct dip in the deck just behind the bow (where those final pesky triangles were fitted).  I didn't want to sand everything else down to the level of the dip as I thought that would make the bow profile odd so I attacked it with a small piece of ply –



A fair bit of filling and sanding later and the deck was in a much better shape – although it looked like ... well, let's just say it isn't pretty   %) %)



Here is a general shot of progress to date. 



It’s the hatches next and then I think I have to start worrying about the mahogany planking.  I might sit and ponder on that for a while!

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #13 on: March 01, 2014, 05:08:53 PM »

Hi Greg, nice job, I am going to be back in business soon building a Dumas Chris Craft for my Niece I managed to get a Kit from the US at a good price, but then found I have to pay VAT and handling charge £36.25.t
Not that keen on building from kits but at least its a start.



I have built one of these 2 years ago, but recently sold it.


Regards
Mick
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #14 on: March 01, 2014, 09:19:52 PM »

Greg.....a few weeks ago we had a thread on clear gloss marine coatings & the product was Trigoginis?.........[totally incorrect spelling].......Stavros.......please correct me

It was a totally natural product ....I have never seen any similar result....suffice to say there was no imported for Australia  >>:-( ......Derek
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #15 on: March 02, 2014, 09:46:40 PM »

Nice to see you back at the boatbuilding Mick.  Will you let us follow your build here?  Please ?  Yes, importing stuff from the US (or anywhere!) can get pricy - witness Martin's experience with his imported jam! http://www.modelboatmayhem.co.uk/forum/index.php/topic,46435.0.html

Nice job on your CC runabout, out of interest what motor did you install?

Derek - were you thinking of Tonkinois?  I haven't used that myself although I know someone who used it on a 1:1 scale boat .  Gorgeous finish!  I haven't finally decided how to finish my boat but I do intend to end up with a nice shine  :-))

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #16 on: March 02, 2014, 10:33:01 PM »

Now that is what a hull should look like  :-)) -not plastic but all wood .

Looks like the Dumas instructions are not perfect on your kit neither ,solving some issues is kind of fun but not if you have glued your self to corner. Good call making the supports for front deck planks.

And the le tonkinois varnish ... I used that on the Diva and it sure makes stuff shiny, but wont use that anymore, it cures too slowly so dust WILL ruin the finish unless you have a sealed paint booth...

I will try to use epoxy as the finish coat and polish that on my Chris Craft, if you will epoxy the hull anyway? -then why not try and polish that.

-Pate
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derekwarner_decoy

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #17 on: March 03, 2014, 01:37:14 AM »

Thanks Pate.........le tonkinois varnish ....that was the name I was trying to remember  :embarrassed:.............Derek
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #18 on: March 03, 2014, 11:05:08 AM »

Hi Greg, the motor came with kit, it was a 6v dumas brushless, I don't think there included now, by the way I use 2 pack clear lacquer on all my boats


Regards
Mick
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #19 on: March 03, 2014, 01:34:31 PM »

I used Le Tonkinois on my Riva here:

http://www.modelboatmayhem.co.uk/forum/index.php/topic,9714.0.html

The results are superb, but it was a lot of work, 10 coats rubbed down with 1200 wet & dry between each coat. Each coat was allowed to dry for at least 3 to 4 days before rubbing down in order to ensure it had fully hardened.

Dust was a real problem, and I think it always will be unless you have a paint booth with dust extraction.

To minimise dust I:

1. Used a new good quality foam pad for each of the final coats in an attempt to cut down on debris carried over by the pad.
2. Ran the hoover in the workshop for a while before varnishing, well, the hoover was outside with the suction tube in the workshop.
3. I bought a new lightweight decorating sheet, supported it across the varnishing area and pulled it over the boat whilst it dried.
4. Left an open bucket of water in the workshop. Apparently it attracts dust, but the jury is out on that one.
5. Left the flouro lights on whilst the varnish dried. They create a little static and attract dust which falls off when turned off.

Despite all that I still got some dust on the varnish, but it was significantly reduced and I think was as good as I will get without a professional spray booth.

Ian
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #20 on: March 03, 2014, 04:00:14 PM »

Quote
I have a question relating to the fittings - the chrome finish on these is not the best, and I know others who have passed this way have taken the trouble to remove the chrome, properly finish and polish the fittings then re-chrome with a kit

  Problem with Mazac is that it will always be Mazac. If you're wanting a top class finish, it has to be on a top class base material so you may have to think remaking the bits from Brass.
 
  Regards   Ian.
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #21 on: March 03, 2014, 06:28:14 PM »

Thanks for all the comments and advice guys.  On the finishing front, I will probably put several coats of polyurethane varnish over an epoxy base then cut it back and polish.  I know the traditional varnishes produce a superb finish but as  Ian  (boatmadman) says you do need to work pretty hard at it. Beautiful job on the Riva Ian  :-)).  Varnish is also a fairly soft finish compared to modern coatings and I have a tendency to bump into things!   :} :}

No Mick, Dumas  don't provide a motor any more.  They do recommend their 6V one but I didn't realise it was a brushless one.  I have bought a CEM 750 after a discussion with the folk at Cornwall Model Boats (very helpful that lot  :-))).  I also have a 1250 kv brushless sitting around that I will try at some stage.  I don't want to break any records but I do want the boat to look like it will give its passengers an exciting ride  ;)

As for the fittings, t'other Ian (Circlip) is, I fear, quite right.  Reading other's accounts of trying to rejuvenate the Dumas fittings suggests it ain't straightforward.  On balance I think that this time I will spruce up what I have as much as possible but I will avoid re-chroming or scratch building.  If I get keen in that direction in the future, I can always refit the boat with better fittings.

Weather's getting better at last - but I still need the heater on in the workshop.  Roll on summer!  O0

Greg

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #22 on: March 10, 2014, 12:59:43 PM »


I seem to have had a bit of "modeller's block" just recently - I keep looking at the boat and doing a little sanding but I haven't made very much progress.

I did swear at the cheap plywood (again  <*< ) when I tried to fit the curved capping piece across the transom.



 >:-o >:-o I replaced it with two thicknesses of the 1/16” birch ply – much easier to bend into place, and so much nicer to work with.  That's it in place and sanded to shape in the picture above.  :-))

I have made the hatches as per the Dumas instructions.  The jigs that the hatches are formed over go together easily, but you do need to take great care that they are square and flat - my engine hatch jig wasn't perfectly flat, and the hatch has a small twist in it which means it doesn't lay flat on the hull frames.  I will try and fix this by building a framework under the hatch (as others have done to represent the full size hatch framework) and I hope that will pull it straight.  Anyway, here are the hatches on their jigs -



and here is the engine hatch with the surrounding pieces laid in place.  Not glued just yet.



I have also been thinking ahead and pondering on water cooling.  I'm not sure I need it (and Pat Matthews suggests in his book that boats like this don't really need it), but it is clear that fitting it after the boat is finished is going to be a heck of a lot harder than doing it during the build.  I decided I would put the necessary plumbing in.  If I don't need it, that's fine (and I can simply direct the water straight from the inlet to the outlet for scale effect!).  If I do, then it's there.  I plan to follow the example of others and have the outlet for the water through the exhaust pipes.  The starting point is to drill a couple of small holes in the appropriate places on the transom -



and that is as far as I have got at the moment.  I won't actually fit any piping until the mahogany planking is finished, but I want to make sure I have some pilot holes in place before I do the planking.

Nothing for it - I am going to have to get those mahogany planks out of the box!   :}

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Re: Building a Dumas Chris Craft Runabout kit
« Reply #23 on: March 20, 2014, 06:42:58 PM »

Hi Greg, I made a mistake the motor was brushed.
I have had big problems with purchase of a kit from the US, it was listed as The box has been opened and there may be a few parts missing. When it arrived someone had started to build it, this is what was missing, all the hull frames, stem, keel
deck beams, birch hull planking, rudder kit, propeller, drive dogs & couplings and some chrome deck fittings.
After several messages going back and forth I put in the hands of ebay resolution centre they sorted it very quickly, sent me via emails labels for customs and returns to print off, given a full refund.
This US trading centre has quite a few model kits with the same wording IE the box has been opened and there may be a few parts missing. the price looks attractive but beware.


I have now bought a kit from the UK, all present and correct 
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Re: Building a Dumas Chris Craft Runabout kit
« Reply #24 on: March 28, 2014, 04:28:47 PM »

Hooray!  Back up and running again!  Well done Martin  :-)) :-)) :-))

Mick - sorry to hear about your bad experience.   {:-{ Good that you got sorted and ended up with a proper kit.  :-)

I mentioned before that my engine hatch had a small twist in it.  I had hoped to correct this with a scale-like hatch frame, but in the end decided that a straightforward solution was best.  I cut a diagonal beam that had a curve in the top that pulled the hatch straight, and it then fitted just fine.



(Before I started this, I did contemplate doing a proper hinged double hatch as in the full sized boat, and even bought some small piano hinges.  In the end, I decided that was for my next boat, and that this one was presenting quite enough challenges without adding to them!  :} )

Nothing else for it, got to start the mahogany planking.  The very first plank goes along the centreline and ought to be entirely straightforward.  The tricky bit is deciding how much to glue down at one go.  Using CA it is virtually impossible to do the whole length at the same time (and using any other glue, how do you clamp the plank in place?), and the Dumas instructions suggest doing a 6” section at a time.  What they don’t explain is, having got your plank partially stuck down, how you then get glue under the next section without snapping it off – like I did.   >:-o   Some who have done this before recommend using kicker on the CA to speed things along.  I tried this on the very first section and managed to glue it crooked.   >:-o >>:-(

In the end I didn’t use the kicker, and I put glue under the plank by squirting some CA under the plank as far as I could go while holding the boat vertical.  The glue then ran down towards the previous glued section.  I gently waggled the loose end of the plank to “pump” the glue into the joint.  I then laid the boat down and held that section in place until the CA had grabbed.  Here’s my first plank!



When I got to the bow (I had started fixing at the stern as this looked nice and easy), the twist needed to get the plank to lie against the hull meant I did it in 2” sections rather than 6”. I did use the kicker here, and found the whole bow area quite difficult to get right.  It really didn’t want to lie flat against the hull.  In the end it did!



And the next couple of planks were equally annoying.  There is a fair bit of twist to get into these planks in the last 3 inches or so, and I wonder if wetting or steaming would have helped.  Brute force won in the end.  O0



After this, the rest go pretty easily out to the chine.  Here’s the first side completed and already with some filler in the gaps!



On the subject of gaps between the planks, I was using the bottom as a trial to see how well I could butt the planks together.  (The bottom will be painted in the finished boat so a little filler won’t notice  %) ).  I found that, firstly, I needed to scrape away any glue that had oozed out –



and that planing a small undercut on the plank edge helped a lot.  I made up a jig from scrap to hold a plank so I could run a block plane along the edge. 



The process I don’t understand is how to cut the join between the bottom and side planking at the bow.  The Dumas instructions and photos aren’t particularly helpful.  The first photo appears to show the forward ends of the bottom planking sanded to a chamfered edge, but the second shows the side planking butting up to a square edge. 





Before I go any further, does anyone have any guidance to offer?  Should the meeting of the planks be an overlapping joint or a butt joint?  Help!!

Greg

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