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Tacit

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Good evening all, I am on a quest for inspiration and knowledge, I have recently acquired a Thompson T24, 10hp Bukh inboard, that is now fairly empty of the mush that was her previous internals and awaits some fresh wood, I have some questions as you can imagine! Is BS 1088 marine ply acceptable material for redoing bulkheads?, I intend to re-deck her with Iroko, 12-15 mm boards on ordinary beams, cotton wool-turpentine-bees wax caulking, beaten in, and Jefferies Marine glue No2 in between the boards, What is the optimum width of board for a 24ft boat, should the boards be square edged or angled at say 100-120 degrees? whats the optimum gap between boards, sprung or straight? can the cabin roof and sides also be made of Iroko?

After I have cleared out the insides, what do I scrub the internal hull with? seems to me that wet/dry/rot fungus have been spreading about the boat?, What do I paint the inside of the boat with, the outside is blister free and no osmosis, good gel coat and only need cleaning. Any help would be appreciated!

The Bukh was "born" (delivered) on 12/12/80 and hand turns and looks like she will go well again, any spares out there? she need an alternator,

no doubt more questions will arise,

any advise is welcome, as the man said

there is not a moment to loose!

Q
 
G'day Tacit and welcome to the YBW forums.

Marine and construction grade ply as used on building sites use the same water resistant glue, the only difference is construction ply will have small voids between the layers. this is still good to use in bulkheads and will cost a lot less, however, you will be limited in top veneer finished available.

That old Buke should have a generator under the flywheel, not sure they had alternators on them back then, hope someone tells me I'm wrong.

I would advise you to spend your time and dosh on getting her safe and the engine sorted first, then see if you have anything left for items like re decking.

Avagoodweekend......
 
Hi Tacit and welcome to the night shift.

You sound as if you know what you're doing in terms of the wood structure work, but on that waterline length, isn't iroko a bit heavyweight ? It looks good, lasts well, but is a bit of a pig to work easily.

There was a lot of discussion with a forumite called Cuchilo (who's a wood craftsman) some time ago about the use of boric acid to deal with fungussed wood. The conclusion was that it was cheap and effective with relatively low environmental. toxicity.

As for painting, have you got a decent gel coat on the interior or is it in poor condition ?
 
regarding the deck. Are you trying to recreate 'classic' build or just want the classic look. If it is just the look then would you consider much thinner boards over a sheathed plywood sub deck. The eopxy sheaved ply keeps the water out and the ( glued or epoxied down) boards provide wear, grip and asthetics.
As suggested the classic boat forum may be a good place.
 
Having used a fair bit of iroko on boats, I would say it wouldn't be my choice for deck planking. Traditional construction usually used softwood (for light weight above the waterline) or teak for it's hard-wearing properties. I can't see it's possible to bend 12-15mm thick iroko planks into the shapes dictated by a 24' hull unless they were very narrow, and that means a heck of a lot of caulking.
I re-decked my previous boat (21' gaffer) with softwood, followed by traditional canvas laid on paint. It was time-consuming and looked absolutely perfect when finished, but started to show signs of deterioration after about 6-7 years (when I sold it). If I was doing the same job again I would use ply, and cover it with epoxy and woven glass cloth. With a coat of deck paint it would look almost exactly the same as a traditional canvas deck, last a lot longer and not leak.
Re the rot - hopefully it's not dry rot as that is very difficult to eradicate. Sarabande's boric acid solution sounds a good idea. If it's wet rot then removing the affected wood and the source of the wet will cure it.
 
Assume you live in UK
For the engine contact Bukh UK in Poole www.bukh.co.uk
For cleaning the inside GRP and painting, Manufacturers such as Blakes and International publish useful material.
For Ply bulkheads any BS1088 would suit. Standard is mainly about adhesive and permitted voids so price varies according to species used in veneers, particularly if you want decorative outers. For example Robbins basic ply is about £70 retail for a 12mm (this is ok for bulkhead etc) up to £170 for teak faced. www.robbins.co.uk for more information.

For your decks not sure I would use Iroko. Heavy, hard to work, odd grains and does not bend well. Traditional laid and payed decks do not get a good press on these forums as they are a devil to keep leak free. I expect most people would advise a marine ply deck, sheathed in glass cloth and epoxy, or surfaced with (very expensive) teak strips , epoxied or Sikaflexed down, not screwed, if you want the traditional look. However, this might be overkill on your boat.
Iroko would be OK for cabin sides if you can find sound boards long and wide enough to do in one piece, although again weight is a problem. Again ply is better and you can splash out on a good veneer such as sapele if you want to bright finish.
Glass hull/wood top construction like yours went out of fashion partly because of cost, but mainly because of rot issues at the joins. The best of the type were the last Golden Hinds which had epoxy sheathed decks and coachroofs which were expensive and time consuming to build but have lasted well. Inside you have the benefit of seeing all the wood structure.

Good luck, and try the Classic Boat forum as there are some real experts watching that

Plenty of information around that covers wood construction using modern materials. You might start with West, the epoxy manufacturers www.wessex-resins.com
 
T24, what a great little boat. What I was going to say has just been covered by Tranona. Yes, BS1088 should be good for bulkheads, you might even use a fancy veneered one if you are going to varnish. I wouldn't use exterior grade ply unless you are hard up, it doesn't seem to last as well or look as good.

Use a bilge paint such as Danboline in the hidden bilges, its easy to apply and has excellent coverage and resistence. Elsewhere inside any marine-grade decorative paint, though it may need to be comparable with whats on already. Chandlers carry info sheets regarding priming etc.

I agree with Tranona's remark about iroko as a decking material, think you will regret that. Rot is mostly caused by fresh, not salt water, so its likely due to rain penetrating a leaky deck. If its a surface dose of wet rot then a boric acid-based gel will treat it, but if its dry rot (illus. here) you'll have to be radical in cutting out affected timber.
 
Thanks Oldsaltz,

point taken on the plywood and engine, marine ply is the only way forward, main concern on whether lloyds approved is essential or just recommended, no doubt you get what you pay for

happy sailing
 
Thanks Sarabande,

I work best after midnight, my thinking also re the weight but using thinner gauge iroko than the original plywood and glass and resin hbe same weight as previous deck, what do you think, thanks for the boric acid info I'll follow that up

Gel coat inside is patchy some still good other places poor however GRP is in pristine condition, what d'you recommend? Speed and cost are important but secondary to a proper job
 
Hi pcatterall

a bit of both I suppose but most important is the longevity and soundness, if done properly the laid deck can be dry and outlast all others, I want to avoid ply and epoxy if at all possible, thanks for the advise, all helps towards final decision
 
Thanks srp01983

point taken on the weight issue perhaps thinner boards , jury is still out,

thanks for the rot advise Boric acid seems the way forward with that issue
 
Hi Tacit

Intrigued as to why you want to avoid ply and epoxy when your objective is "longevity and soundness". Perhaps you would care to share your reasoning with us. As most posts have suggested iroko in the traditional laid form with large numbers of screws and seams is perhaps not ideal, particularly on a boat of your shape which will need severe curves if you want a "swept" effect.

From the way you described the condition of your boat inside "mush", using "traditional" methods is almost certain to start that process all over again, no matter how good your workmanship, because freshwater will get into the structure at some time and undo all your hard work. Making the boards thinner to reduce weight will only make it worse, not only because you will have even more difficulty getting the edge curves, but the deck will be less stable. And experience shows that Iroko is even more difficult to work than the more common and more expensive teak. However, Iroko makes excellent deck beams and looks great as varnished trim in the cabin where you can use small sections in short lengths avoiding the twists and sets that large sections tend to suffer from.

You may be reading too much from the failure of the original deck. That will have been laid with polyester resin, which time has shown is totally unsuitable for the job for the very reason that water gets underneath it and rots the ply. This does not happen with a deck sheathed in epoxy because the epoxy makes a chemical bond with the ply. I feel pretty safe in saying that any boat professionally built now with a wood deck would use this method and sheath with either glass cloth set in epoxy or teak set on epoxy or Sikaflex without any fastenings. Most of the failures of laid decks on either GRP or wood substrates start with water getting in through the fastenings - bungs popping out like a porcupine is a good description.

One of the joys of using these fora is that most posts tell it like it is. There may be shades in the advice, but posters have nothing to lose and are usually trying to help others avoid mistakes. In my original post I referred to published sources. There are many others, both books and mags like Classic Boat, Wooden Boat from the US and Watercraft that have a constant stream of useful articles about using wood in boats. Humbly suggest that you do lots more research before you commit yourself to a course of action. Sorry if it sounds like a lecture, but advice based on over 30 years as custodian of a Ply/wood boat, still in (probably better than) new condition through the cautious adoption of modern materials.

Best of luck with the project. If done well you will have a boat to last a lifetime!
 
Hi Tranona,

Yes, I'm in mid-wales, many thanks for the information re. the Bukh and the plywood bulkheads, 12mm will be perfect for the bulkheads!

Also thanks for the advice on the Iroko decks, I was trying to avoid ply and epoxy, but it looks more and more likely that this may be the best option! However I have about 30 square metres of 30mm thick 20 year seasoned iroko, and I'm a firm believer of using what you've got, but its looking more and more doubtful re the Iroko deck.

Thanks for the epoxy advise also, I will chase these up
 
Thanks AndrewB,

most people agree with you and have said she's a fine craft, albeit more of a fine tub at the moment, do you have any specs or designs or indeed any further info on these craft or her designer, Guy Thompson.

Very sound advice on the internal paint though my trad. laid Iroko deck is looking more like a pipe dream with every reply
 
Hi Tranona,

My thinking behind the Iroko deck were two-fold, I have it in abundance and on many forums I visited traditional laid decks were felt to be superior to Ply and Epoxy, aesthetically and in the longer term re water getting under the epoxy at some time and rotting the ply within a short time, however I do take on board your sound advice re the leaking trad decks, I had hoped to screw from underneath

I agree with you wholeheartedly about the fora, they are professional and I have founf the advice very useful, in addition you may lecture me all you want -I need it- I am very appreciative of the time people have taken to answer my questions, I will have many more, no doubt,

safe sailing
 
Hi Tacit,
Just came across your post - I also have a T24 sat on the drive, fully stripped on the inside. I have just cut the bulkheads from 12mm marine play and the first fit doesnt look too bad! Am intending to glass in with epoxy and biaxial. First want to sort out the mast step arrangement as once they are in this may be more difficult. Spent the winter totally rebuilding the engine (Dolphin 12hp) and thats sat in the garage waiting to be refitted. When I aquired the boat the deck had been replaced with ply and then fibreglassed over - am hoping I dont find too many horrors when I come to look more closely and refinish.
Anyway - just wanted to say hi and maybe we can compare notes further at some stage?

Rgds

Alex
 
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