Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: Nottingham J class build  (Read 462 times)

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Nottingham J class build
« on: August 31, 2017, 05:45:25 PM »

My first love has always been sail, model and full scale, and for some time I have been lusting after one of Alan Horne's J class hulls.  Finally I have bitten the bullet and am now the proud possessor of the hull and the laser cut parts to complete it.  This is the full hull Nottingham version rather than the original Canterbury one.  (If you are confused by this, you can do no better than to visit Alan's website here.)

Alan provides the hull and the ready moulded lead ballast to fit, as well as the wood parts to build the internal structure and deck (as well as a stand).  Everything else you provide yourself, so I guess you need to understand a little about how a model sailing boat works.  Although I have a Victoria and a Dragon Force 65, my knowledge of larger models is a bit sketchy on some of the details, so I will be learning as I go along!  O0

The pictures below show the hull as collected from Alan.  It is a lovely moulding, smooth and unblemished, and I dread the first scratch!  I am following the instructions provided by Alan (read them on his website) pretty closely, although I will point out if I diverge from them (and why).  The first step is to float the hull with the ballast loosely in place and confirm that it is level in the water.  The pictures confirm that it is spot on, which is a credit to the builder.  I had to fill the bath pretty full to get the keel off the bottom!

Next step is to fit the rudder, which requires drilling holes in that pristine hull.   :o   See how I got on in the next exciting episode!

Greg

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #1 on: September 02, 2017, 01:50:26 PM »

 Fitting the rudder requires making holes, ideally in the correct place.  I followed the instructions to situate the hole in the hull, taping a 10mm drill down the back of the keel and marking where the tip touched the hull (pic 1).  A deep breath and a hole is drilled, then gradually enlarged to take the rudder tube. The tube itself needs a fairly acute angled cut to match the hull, and I used a tapered dowel to hold it firm while the cut was made (pic 2).  The hole was then teased out until the tube was a good fit – and yes, I did chip the gel coat (pic 3).   >:-o   Something to fix towards the end.


The heel fitting which holds the rudder at the bottom of the keel was reasonably straightforward to fit, and I did take note of the instruction to countersink the fixing screw to make sure the ballast seated properly at the bottom of the keel moulding.  I did need to improvise an extended allen key to do this screw up, as space down there is pretty tight. Then check that everything fits and the rudder moves easily (pic 4).


At this point I stole an idea from some American J class builds, and put a small ply dam just in front of the rudder tube (pic 5).  This is to allow a pool of epoxy to surround the tube, which almost guarantees a waterproof join and provides good solid support for the tube (pic 6).  I taped up the bottom of the hull to stop the epoxy dribbling through, although a little did squeeze by and I found I had a small plug of epoxy in the tube when it was set.  Easily fixed with a drill or two.


I was now finished with the rudder and moving to work on the inside of the hull, so I took some steps to make sure I didn’t damage that lovely hull finish.  First, I put a coat of wax over the outside, then ran some masking tape along the top of the hull (pic 7). I then taped some plastic sheeting over the hull to keep out all those drops of glue, sharp tools and sticky fingers that would mar the shininess (pic 8).  Time will tell if it works!


Next will be fixing the ballast and building the internal structure.  Everything seems to be going OK at the moment.  :-)) I wonder when it will go wrong!  ;) Fingers crossed!


Greg

 

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #2 on: September 08, 2017, 06:03:10 PM »

 The next step is to fix the ballast in place.  The instructions spend some time emphasising the need to remove the odd bump and lump in the layup to allow the lead to sit as low as possible in the hull, so I spent some time with the Dremel flexi-drive grinding out spots where the lead appeared to catch (leaving a useful grey mark on the hull).  (An essential tip – don’t drop the lead into the hull without a piece of string on the bolts to lift it out.  %% )  After a while I felt I had just about exhausted this process, although the lead wasn’t appreciably lower in the hull than it had been when I started.  I suspect the inside of the hull was a pretty fair moulding to start with.  :-))


At this point I followed Alan Thorne’s advice to remove a section of the ballast to improve the sit of the boat in the water.  I suspect this would be frowned upon by those who race, but I have kept the removed part against the day it needs to be replaced.  Then it was out with the epoxy and a gentle pour to fill the gaps around the lead.  I had to stop when the epoxy reached the level of the cut out section or it would simply have filled that space.  (Pic 1) When the first pour had cured, I sealed the gaps between the cutout section and the hull with blu-tack and poured a little more around the rest of the ballast to seal up to the top of the lead.  I did want to make sure that any water that might find its way into the hull could not hide away between the lead and the hull moulding.


Once the lead was firmly in place, it was time for the internal wooden parts.  The strips provided for the inwhales which support the deck around the hull edge were shorter than the hull so two needed joining together, which I did with a scarph joint.  I find this easiest with these small sections if the two pieces are tacked together with a couple of drops of superglue, the scarph is marked and cut on both pieces at the same time, then the pieces are popped apart, one is reversed and the two glued together.  I hope the pictures (2-5) show this well enough.


The bow and stern fillers came next. These need some sanding to fit, but I was a little too keen in some areas so the parts tended to slip down below the level of the hull.   :o   I fixed a piece of scrap to both parts with double sided tape to hold them level with the hull for gluing (pics 6, 7), then fitted the inwhales (pic 8 ).  These were glued in with epoxy thickened with colloidal silica, and the help of a stiff batten around the outside of the hull – the hull is still very flexible around the top and lots of point clamps runs the risk of inducing a ripple in the hull (pic 9).  Now I could dry fit the rest of the beams (pic 10).  Starting to look the business!


Happy modelling!

Greg

 

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #3 on: September 08, 2017, 06:12:18 PM »

 A couple of small points.  First, I drilled a shallow 1mm hole bang on the centreline right up in the bow (not too deep – you don’t want to pop out of the hull!  {:-{ ), pushed a small panel pin into the hole and looped a piece of thin twine over it (pic 1).  With a weight hanging over the stern from the twine, this acted as my centre reference for all the subsequent fitting, but could be easily moved aside for trying the fit of parts.  I also found that the mast deck (the part with the D cutouts in the last picture above) needed some support between the beams so added some scrap to stop it falling into the bottom of the boat (pic 2).  The instructions suggest this should be glued and screwed to the beams, but I have dispensed with the screws.  I have considerable faith in modern glues and am happy that gluing alone will be more than strong enough to hold everything together.  I hope!


Greg

 

Martin (Admin)

  • Administrator
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 16,247
  • Location: Peterborough, UK
    • Model Boat Mayhem
Re: Nottingham J class build
« Reply #4 on: September 08, 2017, 09:20:11 PM »


Looking good Greg!   O0
Logged
"This is my firm opinion, but what do I know?!"    -   Mayhem FaceBook Group!

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #5 on: September 08, 2017, 10:26:15 PM »

Thanks Martin - although the photos make it look like I do my gluing with both eyes closed!   :embarrassed:

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #6 on: September 12, 2017, 04:54:20 PM »

 Having got most of the structure dry fitted, I then started the gluing.  For this I mostly used Gorilla glue, which seems to glue almost anything to almost anything else pretty effectively.  You do need to clamp pieces in position as the glue foams and expands, and might push a piece out of place if not held firmly.  Pic 1 is the mast deck glued in.  The instructions suggest cutting the hole for the mast tube before fitting, but I felt I was more likely to get the hole exactly central if I cut it in situ.  Pic 2 is this in progress, using a burr in a Dremel flexi drive to open the hole out, and pic 3 is the finished hole.


Pic 4 is the mast tube and the marked out lower support, which sits down in the hull and locates and braces the mast tube.  I made a mess of cutting this hole and had to add a piece to cut a new hole as you can see from the dry fitting of the tube, pic 5.  The mast tube normally comes with the kit, but Alan Horne was out of stock and pointed me to PJ Sails for this part (and I also ordered most of the hardware I think I will need from here, not to mention a suit of sails). I commend Peter Wiles for great service – I spoke to him before I placed my order and mentioned I really needed the tube now, so he took my address and posted it to me before even receiving my formal order, let alone any payment. Thanks Peter!


I didn’t complete the installation of the structure at this point as I still had to make and fit the sail winch assembly, so that was the next step.  I did some experimenting and found my sail winch (a Hi Tec HS-785HB) makes 4 full turns on the full throw of the transmitter stick.  That amounted to about 50cm of travel, which was rather more than I believed I needed. As my transmitter (Planet T5) has no end point adjustment, I initially thought I would need some sort of physical stop on the transmitter.  However, I reckon I am going to need about 25cm travel so the simple thing to do is use a 2:1 on the winch line.  This would have several effects –
1.       I get the correct range of movement – good
2.       The strain on the winch is halved – good
3.       The time to sheet in or out is doubled – bad
So two good things and one bad.  As I am not going to race the boat (at least not seriously), the sheeting speed isn’t critical, and I hope for more of a stately progress around the lake as opposed to a frantic flurry at a mark.  So I went with the 2:1, with an elastic to keep the tension on the winch line.


The suggested sheeting system uses a slider on a rod or track.  Alan Horne recommended Silent Gliss curtain track, but I looked at the price (over £20 for a 1 metre length) and decided I would use what I had to hand.  This turned out to be some 8mm carbon tube and a sheet of PTFE.  I made up a PTFE slider using the brass screws provided for the wooden parts, and although I might have done a neater job, it slid very nicely along the carbon tube (pic 6).  I then lashed together a trial setup to make sure I hadn’t made a complete faux pas somewhere (pic 7), and everything seemed to work fine.  The elastic in the picture is a little fierce, but was all I had to hand.  I will substitute something a little gentler in the final setup.  A close up of the jury rigged slider is in pic 8.  This whole assembly is removable from the hull, so if it turns out to be less than effective, I can modify or replace it fairly easily.  :-))


Once I had convinced myself I could make this all work, I was ready to install the fixed part of the sheeting system in the hull and complete gluing in the wood structure. However, before that I acted on a suggestion from Alan Horne, namely to fit something to the ballast to provide a lifting point that didn’t rely on the deck and hatch structure.  I had some stainless M4 studding, so that seemed to fit the bill.  I drilled a hole in the aluminium strap that holds the trim weight in place and fitted the studding, pic 9, in what I judged to be the balance point of the hull.  Then the remainder of the wooden parts were glued in, assisted by various clamps and elastic bands, pic 10.  In this picture you can also see the base for the sheeting system in place, along with the removable section which carries the winch and moving parts.  You can also just see on the right clamps keeping the hull beam within tolerances as the glue dries.  The top of the hull is still quite flexible and can easily be pushed out of shape, something to watch when gluing these pieces in.


Coming along nicely! A few more details internally then on goes the deck.  :}


Greg

 

SailorGreg

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 554
  • Money talks - it says goodbye
  • Location: Hayling Island, Hants
Re: Nottingham J class build
« Reply #7 on: September 16, 2017, 05:52:19 PM »

 Well, the “few more details” I mentioned last time seem to have taken a little while  %) .  Firstly, I found that the two longitudinal pieces that form the edges of the main hatch were curved.  Not sure why, the sheet of ply they came from seemed flat enough, but there it is.  They were both curved the same way, so the hole for the hatch was offset by up to 2-3mm (pic 1).  At first, I thought I would just put a couple of small beams in at the midpoint to push/pull the pieces into line.  But the hull isn’t completely rigid, and when I tried it the hull edge moved as much as the curved piece. Hmmmm!



After some head scratching, I took a piece of 1.5mm ply and cut it to fit as shown in pic 2.  The straight edge of the ply keeps the port piece straight and is braced where there is a lot more rigidity in the hull.  The half beam that will form the front of the hatch opening then pushes the starboard piece straight as well, so problem solved!  I did wonder if I needed a piece on the other side just to balance the boat, but decided the weight of this was not going to make a lot of difference.


Around about now I tried lifting the hull with the piece of studding I had installed and noticed that the aluminium strap the studding is bolted through flexed slightly.  I worried that this movement would be transferred to the deck when I lift the finished boat, so I decided to put a self-tapping screw through the strap and into the ballast next to the studding.  In principle this is straightforward – drill a hole, put in screw.  But I needed to drill a hole down in the bottom of the hull between the various pieces of wood I had just installed. I couldn’t get any power tool down there so had to resort to a hand drill (pic 3).  Anyone who has tried drilling lead will know that it is a real pig  >:-o . It took me forever to drill the hole, but I persevered – pic 4 shows the screw in place.  And there was no discernible movement of the strap when I lifted the hull.  Hooray!  :}  I also added a small piece of ply to stop the studding waving about too much (pic 5), although I am not sure how necessary that will be in the end.


In the build manual, Alan Horne places great emphasis on making sure the inwhales and other structural pieces are at or just below the level of the hull edge to allow the deck to sit flat and true.  I was not as careful about this as I should have been, and when I checked with a straight edge across the hull, there was a bit of a problem in a few places, especially around the mast deck area.  Here the straight edge was 1-2mm above the hull edge.  <:( The inwhales are fairly soft wood, so will sand down to the correct level easily enough, but the ply pieces are made of sterner stuff.  I resorted to my random orbit sander with some 120 grit paper.  To make sure I didn’t take the hull edges off as well, I started by running a permanent marker along the edge of the GRP shell.  As soon as this began to disappear, I stopped sanding in that area.  A long, dusty period later I was back where I should have been all along.  Pic 6 shows this process with a little of the black marker still visible in the bottom of the picture.  I finished the sanding off with a rather more gentle progression along the hull with a piece of wood with some finer grade paper glued to it, pic 7.  If you are building one of these lovely models, PAY ATTENTION TO THE INSTRUCTIONS!  I will in future.  O0


I then tried the deck on the hull (pic8).  I am very happy to report that the laser cut holes for the hatches lined up exactly with the beams, and everything looked like it fitted pretty well around the hull.  But still a couple of things to do before gluing it down.  Next time.


Happy modelling!


Greg
 
Pages: [1]   Go Up