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[tonyH]

The fly-screen....

[zooma]

 My prop shafts have now arrived so I can make a start on getting these fitted into the hull - and this has finalised my on/off choice of single shaft drive or twin - its going to have twin shaft drive drive. This will also be more "authentic" and will be my first twin brushless powered model.


I have been following the 41" Huntsman build by ukmike as that is another reasonably large boat that is being fitted with twin screw drive, and Mike was kind enough to offer some advice regarding the type of brushless motors that could suite this hull.


My Corvette is 48" long and 13 7/8" wide and has a round bilge hull form, so the comparison is not quite so obvious, other than the fact that they are both reasonably large sports boats that will both have twin shaft drive - and that was enough to encourage me to make the decision and to ask for some information about the motor choice Mike was using as I was not at all sure what to try first in this hull.


I will be fitting a pair of water-cooled alloy motor mounts and they have the advantage of being very flexible insomuch that they will accept a fairly wide range of motor sizes, so if I don't get it right, it will be fairly easy to unbolt them and replace with another choice.


Fortunately brushless motors of the size I think I will be using are fairly inexpensive and anything that may not shove this big lump along quickly enough will be more than adequate for some of my other classics that I am working on as they are all smaller (and lighter!) than the Corvette!

[zooma]

The two prop shafts and rudders are now fitted and the water cooling pick-ups will follow next.  I also cut a suitable plywood plate to fix a pair of alloy water cooled motor mounts, so that will be done next.


.......or it should be - unless I get distracted again!


Every time I fit the superstructure back onto the hull I look at the gap at the transom end where the rear cockpit will be.  Looking at the various Corvette models that I can see online suggests to me that this is an area on this model that could be improved.


Various loose drop-in floors seems to be the order of the day and that is what I envisaged having to do too......but late last night when I should have been coming in from the workshop I had a "light-bulb" moment and a few minutes later the bandsaw was cutting out some plywood and I added a fixed cockpit to the rear of the cabin.


The whole superstructure/cabin assembly on the Corvette lifts off of the hull in one piece, and now the rear cockpit lifts off with it so basically the boat has a top and lower half making access to the hull very good and putting the" lid" back on really easy!


Maybe when I take another look at it this morning I will not be so impressed - but I went to be last night quite happy that I had solved this problem.

[zooma]

Does anyone know how to compare the power output of a single brushless motor with a pair of smaller brushless motors?


I have had problems deciding whether to power this Corvette with a single shaft driven by a 3648-1450 motor or to use a pair of brushless motors. I have decided to fit two shafts so now I am thinking about the power I need from a pair of smaller sized brushless motors to give a comparable performance.


The 3648-1450 motor has plenty of power to drive this model along at a good pace, and make the white water that I love to see behind all my model boats (not my TID tug!) but trying to work out how a pair of smaller motors can perform against this known power is not proving to be so easy for me to work-out.


I would like two smaller motors to give the same power as my 3648-1450, but with two shafts to drive there will be a loss of efficiency to consider too, so I think they will need to give more power than the single motor to make a similar comparison.


Can anyone help with this please.

[ChrisF]

Hi Bob

Should have put it on here but I've put my thoughts on your Javelin thread.

Chris

[zooma]

Thanks Chris,


I will take a look.


Bob.

[zooma]

I just cut and pasted your thoughts to put them here on the Corvette thread:-



"Twin motors over single don't really add much if anything to top speed and in theory will increase acceleration but that is usually enough with one brushless motor anyway. You could go slightly less power for each of the motors but as space isn't an issue I wouldn't bother. Better to have a bit more power than required as it can be regulated by the throttle or batteries.Number of engines etc. has more relevance with full sized boats whereas with brushed motors they are usually over powered and having more than one motor is more to do with a scale model matching the full sized. My thoughts anyway, which could be wrong!"

Hi Chris,

I am only running twin shafts as it will look more scale like (and make a nice change).

With a Turnigy 3648-1450 motor I know what sort of power it has and that it has enough "grunt" to give the Corvette a good performance.

I was hoping to find out what types of brushless motors would be needed to achieve a similar performance (if possible) when driving twin shafts, but I was not expecting any increase in performance at all - more like fearing that it would not have any "sparkle".

I have had some good advice about different types of Surpass motors, and their inexpensive prices (eBay or Bangood) will help to keep the cost of buying two motors no more expensive that buying one 3648-1450...and I may even get longer run times too!

This afternoon I made up a suitable (heavy duty!) motor plate and aligned a pair of Surpass motors on alloy water-cooled mounts.

Restoring an old boat means working with old (and often rotten) wood, and this has its challenges - especially this  Sterling kit that originated in 1954. Some of the American model boat kits leave a lot to be desired in the quality department, and this example is one of the worst I have ever seen.

Finding really low grade wood is not good news in any new kit - but give it 65 - 66 years or so to mature (decay)  and soak it in gasoline and you are left with what I have to work with!

I am at the stage now of installing good new wood as needed and the last job (sometime in the future) will be to remove any remaining rotten wood whilst trying to preserve as much of the original as possible . Knitting the old and new together will be fun when I join the old and new together inside the hull as this will mainly involve "bringing the gaps" that are currently occupies by fresh air!

[zooma]

The heavy plywood motor platform has now been epoxied into position and the two water cooled motor mounts have been super glued in place on this platform after everything was in the correct position.


Everything was aligned using solid “alignment shafts” of the same length as the powerflex couplings, and now the motors have been removed so I can reinforce the joint between the mounts and the motor platform.


I have cut some short lengths of carbon fibre bar and pushed them through some of the holes that come drilled along the bottom of the mounts so when I epoxy or fibre glass over them they will give a wider footprint to improve the bonding area to make the mounts more secure.


Ongoing tests with a 120amp Car ESC and different Surpass motors should determine if I am happy enough to fit a pair of these and make this my first boat to run without water cooled ESCs.

[tonyH]

Latest Pics......

[zooma]

Thanks for posting the pictures for me Tony, this restorative work takes time but it is making some progress.


The drop-on superstructure is latched on to the hull and secured with a hook formed as part of the front cabin sides that is located into a slot on each side of the front bulkhead.


As the superstructure becomes heavier this is a lot of weight for these small cabin side extensions to bear, so I have cut them off and will try to come up with a better solution and try to incorporate an idea to help prevent any water that is washed onto the foredeck leaking into the hull.


I don’t like performance boats with drop-on cabins (like lids) that just sit on the deck as they can all be prone to water ingress if they are run in rough water or driven at speed without some form of barrier being added to at least slow the ingress of water - so I need to come up with something for the Corvette.

[zooma]

I have decided to try using a non water-cooled power system on my Corvette - making it my first large r/c power boat to run "dry".


The Surpass ESC have a good reputation and also provide a reverse function so I bought a pair of 120A to go with a pair of Surpass 3542 1450KV brushless motors in the hope that this combination will work well and have enough power to shove this big heavy barge along at a reasonable pace.


On arrival, I liked the look of the ESC and was pleased to see that they came pre-wired with gold sockets on the motor leads and Deans connectors on the battery leads, but I was surprised when I fitted the motor leads to the matching gold plugs on the Surpass motors to find that they were such a bad loose fit that they just fell out!


To test the ESC and matching motors I held the  gold plugs and sockets together with masking tape (!) and everything works well with no problems.  The moulded Deans plug was a very tight fit and proved to be a problem when trying to pull it off of the matching Deans LiPo battery.


With everything working OK, I will be changing the plugs and sockets to some that actually fit each other (!) and changing the deans plug to an XT60 ( or maybe an XT90) as they are basically gold plugs and sockets held in yellow moulded casings to prevent any accidental short circuit  - either in the boat or in transit or storage - and they are the best connectors that I have found over the last 50 + years of working with radio control models.


I am surprised that the plugs and sockets from the Surpass ESC and motors do not actually fit each other properly  as they are clearly the same size - just poorly made and out of a working tolerance. The moulded-on ESC Deans plug was overly tight compared with the other Deans plugs that I have been using for many years on various r/c helicopters and cars, and one was significantly tighter than the other!


Changing the gold plugs and sockets is not a big deal - I prefer to use a bigger size in any case, and this will keep all of my motors fully interchangeable so I can fit them in any models boats that I would like to test them in.


Changing the moulded-on Deans plug is not a problem either as having used Deans plugs for many years I am fully aware of their shortcomings and prefer to use the XT90 plugs on my larger models and XT60 plugs on my smaller models as I find them to give a much more reliable connection, and I also find them a lot less fiddly and easier to solder.

[zooma]

Anyone who has been following my (slow) restoration of this rather sad Chris Craft Corvette will have seen the amount of work and different materials that I have used to bring the hull back into one lump.


The original 48" long hull was planked with balsa wood (original Sterling Kit assembly) but was rotten and fuel soaked in places and needed a fair bit of attention to replace these areas and to replace the badly repaired patches and remove the coating of filler paste that was roughly applied over everything including the balsa wood, rotten and fuel soaked woods, filled patches, planked hardwood, black mould and various layers of paint!


Surprisingly, the filler paste needed to be chipped off of some areas with a chisel, whilst in other places it was happy to almost peel-off in large lumps, but the areas to which it adhered the best included all of the pre-mentioned  - so there was no real logic to how or why the filler stuck to some areas and not others.


Since then some areas of the hull have been re-planked with hardwood that I stripped on my bandsaw, and the  lower bows have been re-made and carved from solid balsa wood laminations, but this still leaves some areas of the original planked balsa wood.


Recently, I have been thinking that I would be happier if I could coat all of the hull exterior with a lightweight glass fibre cloth that could be laminated onto the hull to give a uniform outer-surface and to toughen-up the balsa wood areas.  The finished "shell" would also help to protect the hull against any of the knocks that r/c boats can suffer when sailed every week, year-in and year-out.


Having never coated any hull previously, I have some concerns about what the glass fibre would and would not adhere to permanently as I have so many different materials that I would like to cover, and at the moment, none of these surfaces are "bare" as they have all been painted to make it easier to see where areas needed to be sanded and blended-in to give an acceptable surface.


Rubbing the paint down is not a problem but it will reveal a variety of materials that I would like to cover.


Does anyone have any experience of coating an old hull with any form of cloth and resin over a variety of surfaces?  Any recommendations about what cloth and/or resins to use along with a proven application method would be greatly appreciated as this is a large hull and I would like to find out as much as I can about it before spending a lot of time on it.


........maybe it would be better not to bother and just see how things go and make any small repairs as and when they happen...........?

[ChrisF]

Hi Bob

I use Eze-Kote resin (water clean up) and 1oz/34 g/m2 on my builds but that's new timber and P38 filler.

Z-Poxy 2 part finishing resin and the same cloth would probably do the job on your multi-material hull as it covers all sorts of materials including plastics. If that doesn't cover something then paint won't!

You can use it on your new builds as well so in the unlikely event it doesn't work it won't get wasted. See Deluxe Materials for the cloth.

Chris

[zooma]

Thanks Chris,


I will take a look at Z-Poxy - it sounds like it could be worth a try.


Bob.

[Jukebox]

Hi Bob, Hows the Corvette coming along ?  I also have one, but mine has a fibre glass hull. I also have another wooden one. Mines going through a very slow restoration !  Few other things going on at the moment !


John.

[zooma]

Hi John,


It is really nice to hear from another Corvette owner as it means that I am not the only one that is "enjoying" working on one - and you have two of them!


Are they both the same size as my Sterling kit model by any chance - and if so - where did you manage to find a GRP hull?


The Corvette is a big model for me to work on in my workshop (shed) as I cannot get to see both sides without lifting the model to turn it around and this is not very helpful when I want to "eye" something up!


Progress over the winter will be limited as I cannot take the model outside to do some of the jobs that i would like to do, and as recently as this morning I was considering putting it in the loft until the spring until I can get it outside to do some of the jobs that are not so easy to get to do in a narrow shed (workshop!) and this would clear a lot of bench space that I could use for the smaller models that I am currently building.


I see you have also put a small "barrier" in front of your windscreen to prevent any ingress of water from "deck-wash" - something I have just done on mine.


It would be good to see some more pictures and comments about your two Corvettes on this thread as there really are not too many more than ours in the UK.


Bob.


.........forgot to say how nice it is to see one in one lump - and with the right fittings on it too! 

[Jukebox]

Hi Bob, the model is as i purchased it  (flea bay !) There are quite a few non standard additions that have been added by previous owner, who I think was the original builder. I purchased it of his son who was dealing with his estate after he had passed. Work has been done to a very good standard, I think it just spent a lot of time in a dusty loft or garage. I do have a wooden one as well ! also bought from good ole flea bay. It was listed as old wooden model. that one has never been finished. Also have a 63ft, but that's for another day! lol ..also got a Catalina!  Very smart models. Mine probably going to have to wait until spring now as well, so flipping cold outside at the moment! Nothing dries, paint glue, filler ! I will use the next couple of months to do as much research as possible. Plus all the other jobs i should be getting done ! Was also considering taking a mould of it and maybe make a few other hulls.  Where are you located? I'm in the UK Covid hotspot..Isle of Sheppey kent !

[Jukebox]

The barrier, was to hide a not so good joint ! lol

[zooma]

I am in Rossendale Lancashire  - quite close to Burnley.


Good luck with your research - if your two models were built from the American Sterling kit they will be 48" long and have a beam of 13 7/8", although your glass fibre hulled model may well be a copy (not a bad idea !).


If your wooden model has a hull that is mostly diagonally planked balsa wood, and the same size as mine then it will almost certainly be made from a Sterling kit like mine was.  Some pictures of your wooden Corvette would be good to see - its unlikely to be as rough as mine was when I first started working on it!


There are a lot of good pictures and video of the Corvette online to whet your appetite - most of them are in the USA, but thats where this classic Chris Craft boat was made and I guess its the American equivalent of our Fairy Swordsman or Huntsman in terms of popularity for a home made product.


Stay safe!


Bob.