I have a "make it so" with longnitudanal cracking within the decks first ply, caused by the hiking out turning moment I guess. I took it back to Laurie last year who epoxied some ribs to the underside of the deck to stiffen the decks in the effected area, unfortunatley it doesn't seem to have worked and I am now at a bit of a loss, do I leave it and keep applying varnish, do I have more ribs fixed, or do I sheath the underside of the decks with glass or carbon, any ideas? (Obviously don't want to go overboard on hte weight either!)

Once the laminate on the ply has started to crack, it is very difficult if not imposable to correct. You could try stripping back to bare wood, and coating with a thin epoxy, and then varnishing over this, but if you have movement in the wood this will only crack again. I would suggest taking it back to Laurie, or another boat builder who understands Merlin's in your area, if Laurie is not close to you. What area are you in may be someone can advise a builder.

This seems to happen sometimes - there has been discussion on the CVRDA site about cracking and the general opinion is that you can occasionally get a duff sheet of ply and little hair cracks open up.  I am sure that there will be someone along who can verify this.  Sadly, not a lot seems to be possible to effect a permanent repair - perhaps the epoxy method could work but a lot depends on what the previous finish was.  Epoxy onto oil based varnish is a bit of a no no......

Is it actually cracking, or are you seeing fine lines in the varnish? I had the same problem with Business as Usual, but concluded, after a lot of soul searching that it is a varnish issue rather than ply related.

Do you get a dark witness line in the ply if you wash the deck down? If not, then the varnish is still intact.

The conclusion we drew is that the build up of varnish in the butt joints in the top veneer contracts more than the surrounding thin film. This leaves what on first sight appears to be a fine crack at each joint. Giving it a new top coat will make it go away. The cracsk appeared one year after the decks were varnished.

Jon, Smart Cookie did the same while Peter Scott owned her. It is a ply issue, i can't remember how we fixed it, it was some time ago. Give Phil a call.

I'm afraid it is definatly the ply cracking and not just the varnish

My "make it so" SECOND THOUGHT,  had the same problem as did MAKE IT SO. My cracks were also on the fore deck. Laurie fixed mine this spring and so far so good.

It's been a recurrent problem with Heaven Sent.  Laurie rubbed the decks down hard and revarnished, things are much better but the only permanent (expensive) solution is redecking.  I am not looking forward to the effect of this winter as unfortunately the boat is outside and I am sure freezing of damp decks is the main culprit.

Hi Jon. Is that on Pocket Rocket? Thought it was the lucky one and had escaped the ply problems... Just re-done this with Smart Cookie. Strip back, fillet the cracks (if needed) and epoxy it the only way to stabilize the cracking. Or re-deck. A shame due to strip laminate...
Hope you're still enjoying PR! Hands down we had to get hold of another Make it so for us!
Cheers

Jo I assume thats you good to hear from you and even better you've found another make it so they're quite a rarity I beleive. Pocket Rocket is great and we're really enjoying sailing her,certainly don't want to redeck her the cracks are't too bad I just wanted to sort them. Chris I'll give Phil a ring thanks, Roy do you know what Laurie did to Second Thought?

Jon Smoking had a couple of terrible cracks in the fore deck and aft where my not inconsiderable bulk batters the decks, D.H. sorted them for me and the fore deck cracks are a work of art, the one has vanished the other looks like a pencil mark and a 4H pencil at that! The side decks are still surviving and Smokin has seen a fair bit of sailing since the repair.

Hi John,
I own the first in the line. Make it SO
Had a simular problem with the side decks cracking.
I sent the boat into Paintcraft Nottingham and they made up some thin ply panels and glued using epoxy to the underside of the decks from transom to shroud to act as a stiffener.
The issue being that the ply was too flexible, no problem for the ply but two pack varnish does not like to bend.
This has solved the problem and I will be amazed if it ever cracks again.
Paintcraft also stripped to hull and decks back to wood, spary two pack painted the hull and spray two pack on the decks. Then left to cure for three days in a low bake oven.
If you would like to see how they have made the modification, no problem.
The boat is at home in my garage (high wycombe)give me a call (07785 341153)It does seem a pity that I have had so much work done on the boat to bring her to exhibition standard, and hardly sailed her since.
Considering putting her on the list after Christmas.
Regards John Haynes

Hi Jon, I think what Laurie did to Second Thought was to flow epoxy into the cracks before rubbing down and then re-varnishing. In my case it was definitely the ply cracking. I was wondering if Andy Jones has had a problem with his?

Hi Jon. Yep glad to hear you're enjoying the boat... think we have all the Make it so's covered here!? Apart from the sandwich one...
Not experienced any on the foredeck, only under the helm. (Don't say it....!) Planning to beef it up with a pad/carbon layer underneath should help the cause too. Should still be plenty of lead to hand if weight is a real worry.
Cheers
Joe

I discussed this recently with Tim Gatti of SmallBoatCraft. In 2988's case it is the edges of the ply along the original joints in the outer layer that are lifting, pretty much all over fore & side decks. At the moment the effect is very slight and difficult to photograph (I actually only noticed it after going from satin finish to high gloss), but it's there, and I guess it won't go away,- though might outlast me! We decided that the best bet was probably to 'squeegee' in a very fluid epoxy & refinish.

Having read this thread it sounds to me like the problem encountered by many boats built using Bruynzeel sapele ply , the veneer cracks along the joins about 4 inch strips, i dealt with a couple of Solos which had this problem, tried to get bruynzeel to honour their warranty, they paid to have one stripped, and re epoxied, cured it for a while, but it will occur again, they have now dropped there warrnty

Graham, thanks for the reassurance! But I think you're right, ultimately this is a bonding problem.

I think its caused by tortion.The decks provide nearly all stiffness to the hull & on such a wide hull 4mm ply just aint good enough. I`ve decked my boat twice now,1st time with brunzeel, 2nd with an alternative.I`m thinking of sanding back to wood & epoxying some light weight multistrand fibreglass over the decks & revarnish.I`ve already epoxed woven carbon to the undersides which helped but the lines are beginning to apear again!

It's a very common problem in many classes though, otherwise i'd tend to agree. Any boat decked in sapele faced ply after about 1995 seems prone to this, although interestingly I have yet to see a Driver or Turner built M/R do this. They are put together with a lot more twist in the deck panels than other builders use and this may stop the wood flexing as much either due to torsion or a 13st bum landing on it!!

I'd say it's certainly exacerbated by movement.

Hey Chris,could a 13 stone bum or even two 13stone bums together be the cause of the torsion?

Yes easily, but there is more to this in my opinion. I could be completely wrong but here goes!

My theory was, and still is, that you know your boat is beginning to soften when the inwhales start to split or break away from the knees. This will also be due to torsional flex, possibly due to large bums landing or the boat absorbing energy by moving as you go through a chop.

The plywood issue is certainly not unique to Merlins. We've fixed many GPs and Solos with exactly the same problem, all of them decked in Sapele faced ply. Where i was coming from with the differant build style was that if you were to take a large picture frame and place a piece of ply in it, even glue it in place, it is quite easy to press on the wood and make it flex. 

Many boats are decked with flat or nearly flat panels and there will be noticable movement if you press down on them. This movement works the glue join within the wood, which is not as good as it used to be and causes the join to open at the edges. Solos especially have large side decks which although they are angled there is no twist at all.

The boats built by Kevin Driver and Jon Turner are put together differantly. The side decks are noticably twisted front to back and you will find if you take your same piece of ply and hold it in a twisted frame it will be very hard indeed to press a dent into it. You'll probably crack it first. Obviously if you remove the continual flexing of the ply you ask much less of the glue joins within the ply and they are less likely to open up. Although the wood is tortured initially, in the long term there is far less movement.

Overall this is a much bigger issue than 5 or 6 Merlins, and construction is only part of the problem. The quality of the plywood is nowhere near as good as it once was and this is why boats that are not really all that old are suffering from these issues.

funny... never seen any problems on a chippy boat either...shame you cant get that rosendal ply any more..too expensive to make? 
   Robbins do a 8x4 sheet of 1.5mm sapele faced sheet,its not heavy and is just enough to put some substance back into the deck, we,ve used it on quite a few  boats ,none have had the problem come back,trouble is its around £80!!!

Hello DH, is that a 1.5mm sheet (like a veneer)that could go over an existing piece of ply, or ply with a 1.5mm sapele top ply ? - interested as I've got another use for something like it.

On a slightly different subject - I thought I was getting cracks in my 1 year old 2 pack varnish, (on sapele faced ply of 1995 vintage) but on close inspection, the varnish just seems to have sunk into the grain - as if it's continued to flash off and looks like small cracks, but I'm now convinced theyre not - well I'll keep a close eye on it at least!

And another thing, while I think of it - when I had a bit of 2 pack cured in the bottom of a container I hadn't used - it would peel out and be quite flexible - I hear alot about how it won't flex with the wood - is it just britle when it's thin?

No Km you are right in mat cases two packs bad press is from the ignorant and luddites who refuse to accept that the reason Uffa Fox Jack Chippendale didn't use two pack was that it wasn't available!

I do know that even upto last year the ply shipped to a very discerning boat builder started to crack as mentioned above, the supplier/manufacturer have now changed the glue bonding the veneers and refunded the builder at least some of the effort he had to put in to fix the problem.

KM, see my post at the start of this thread. We have seen varnish lines on Business as Usual - Glen Truswell had the same on all his boats - it is the 2 pack varnish shrinking on the veneer butt joints. You cannot really see the lines until you get the boat in artificial light and "sight" along the decks. 

It invariably happens 1 year after the varnish has been applied.

So you are not alone!

hi kieran, sorry to say its 3 core ply,(.5mm each),my own personal feeling on the ply issue is the core material is not as good as it used to be.

Thanks DH, - it might still be OK - I'd seen a 0.5mm veneer they do, but thought it might not go down completely flat with epoxy under it - a good rollering might get close though.- 1.5mm would probably do just fine. I'll ring you /show you what it's for when I see you next.

Andy, thanks, I read your post and I think it's the same issue - for me it's the wood grain itself the sinks show up in - I'm hoping a fresh lick of varnish will sort it. My reasoning was that the varnish build up was thicker in the grain / joints (OK, only  marginally!) so there was more solvent to flash out than on the 'peaks' where it was thinnest.  

This is entirely due to not sailing and having too much time to look for problems! still, another few weeks to sort them out,Thanks both for the advice!

Make it so, is now up for sale on the web list due to lack of use.
I can comfirm that the side decks are rock solid and only abuse will cause them to crack.
please call if you are interested.

Is there anyone out there can give me info and contacts about re decking my merlin 2987.Rescued her from certain destruction and want to bring her back to life.Cheers.

Hi... two little bits of help here that may (or may not!) be useful.

I was considering redecking my Contender as the builder had gotten into a bit of a muddle and had decks that were hugely overthick (they have to be 6mm). So, the top 5mm were routed off, then 1.5mm ply laid on to finish. Technically the job went well - invest in some bags of sand from B&Q as that is a great way to get plenty of weight spread over a large area, thus avoiding bubbles and depressions. It works well and I am very pleased with the result - the decks are still and sound and less than 0.5mm over thick. 

BUT - Robbins only do 1.5mm in Gaboon so it might be difficult to get nice sapele decks. As the Contender was strip planked in cedar, the gaboon looked good (plus the sheet I had was nicely patterned) but it may not do for a merlin. I'll post some pictures showing the work in progress and the finished job - as siad already,  I am very pleased with the final result.

As for 2987.... you've dome well to save here as she is shown in the book as a destroyed boat. I'm in the middle of restoring 3025 - from just the following year to your boat... redecking is not a cheap option by any stretch of the imagination - are the decks beyong repair or redemption?

Will upload some pics of both the Contender and the Merlin...

D
3025

Just looked - 2987 - an Aln Boatyeard Phantom Kipper called ' Pint Sighs'.

The other place where you can get a lot of advice on jobs like this is the Classic dinghy website, 

www.cvrda.org

D

When all is said and done, you must agree, The Merlin is a Cracking Boat !!!

Hi guys...

Found this thread because I am concerned about similar on "The Dream Machine" the Ron Hall Ian Holt designed Merlin I am restoring this winter.

Anyone have any great tips to add. I am starting to think a re-deck is possibly a good idea because of the added forces going to be exerted by a new rig. 

There are longditudinal cracks in the foredeck, and as I was considering building a stronger spaceframe into the foredeck to deal with the added force from the rig I guess the deck will have to come off.

I would imagine a re-deck would be an expensive option. Guessing at close to £1k all in? Unless the decks are really shot, I would try a few coats of epoxy on the bare wood before some/many layers of good varnish with a lot of UV protection.  I've previously used SP106 to good effect, although the accepted wisdom is that SP320 is more resistant to going cloudy in contact with the UV, so aesthetically may last longer. If the top veneer has lifted a lot, maybe get a little epoxy under it, warmed with a warm air gun to get it to soak in, nice and runny and roller it - also a thin layer of f/g tissue might keep it all together and be all but invisible under the epoxy and varnish. I suppose it depends if it needs to be a concours or a good everyday finish.  hth.

The ply available nowadays is a shadow of its former self in quality. You are much better off keeping the existing unless its shot beyond structural reclaimstion. Carbon or glass on the underside is one option. Longitudinal cracking is common, it usually goes down the manufacturers joins. We have fixed a number of Ron's boats that have done that, these were built just as the ply quality started to decline.

A good resin coat will stick the veneer down, any opening joins may benefit from a Stanley blade just to clean the old glue out. I've seen boats witha near invisible layer of glass on the ply, but this would be difficult to do neatly and not as effective as a layer or 200gsm carbon or glass underneath.

Having taken off the varnish of BAU a week or so ago, I was interested to see that the "cracks" in the varnish we had seen were not obviously there in the sheets of varnish that peeled off (that's a different story). So the story about the varnish contracting & pulling on the top butt joint in the veneer seems even more plausible. We have flaky paint on the underside of the decks which is how the water got in under the varnish, so a layer of glass / epoxy on the underside will cure that.

What to put back onto the bare wood is another question .... glass + epoxy then 2 pack or the traditional route? More ploughing through the CRVDA web site I guess.

All advice much appreciated...

Will be having a good look this week and making a decision

Cheers

In 2005/6 I redecked 3285 (a Bob Hoare composite NSM 2). I would make the following observations which may be of some interest to you. I agree that a redeck could be very expensive if you were to pay to have it done for you but if you are doing it yourself as a labour of love, and for the enjoyment of doing it, then it need not be so. I redecked my Merlin for the cost of two (8 x 4) sheets of 4mm Tiger Elite sapele ply together with some mahogany (well utile actually) for the gunwales, all from Robbins. This, together with the epoxy, colloidal silica, micro fibres and glass bubbles represented the entire material costs. For me some of the advantages of redecking are that it allows you to add bearings and reinforcements for the rigging points for a modern rig and to position fittings like spinnaker sheet fairleads just where you want them without leaving your decks pock-marked where old fittings used to be. If you were to total up the time you could spend modifying an existing layout you would find it mounts up to an appreciable contribution to the time taken for a full redeck! Also, replacing the gunwales makes the redeck so much simpler and quicker! However, a major benefit to a redeck is that it allows you to epoxy the entire underside of the new decks prior to installation, thereby ensuring that nothing will be missed (see Andy Hay's comment above about water ingress on BAU). I used one sheet of ply positioned centrally across the foredeck and I scarfed on the side triangles to achieve the full width at the aft end of the foredeck. This ensured that I would not have the potential weakness of a butt joint anywhere on the foredeck. I then made each side deck in one piece and arranged for the joint between the side decks and the foredeck to be covered by the tufnol reinforcing plate at the shroud and lower shroud entry points. I therefore have no joints in the decks. I then gave the whole deck a couple of coats of epoxy and varnished it using single pack Epifanes varnish. I decided on this finish as I felt it could be more flexible than two pack (and would be more practical to touch in any possible future scrapes) but that's a personal choice and I don't have any particular evidence to justify it!! I appreciate that some of the comments on this thread are referring to butt joints in the surface veneer but I have had no problems with this in the six years since I did the job and I have only rubbed down and revarnished once in that time. The decks today look just the same as the day I finished them and the boat spends the whole season in the dinghy park, only being garaged over the winter. The financial cost was just a few hundred pounds. Obviously if I tried to cost in my own time then it would probably have been economically insane. However, I rescued a good boat and I now have a beautiful Merlin which gives me great pleasure to sail. You will be able to see from the list of boats that contest the top places in the championships that an old boat is never going to win, but oldies can be really rewarding if you enjoy cherishing them. Don't simply dismiss the idea of redecking. If you follow the link below to the photos you can decide for yourself whether this would suit you.

Hi Richard

Thank you for the explanation. Certainly some great points to think about. 

I will make decision this week, when I have more information.

Didnt get to really looking at the decks today as i could only put in a half day, so will do tomorrow.

But i did knock back the Transom and it came up really well. The boat is looking like a really good project so far.

One or two bits on my NSM 3 are starting to do this and will get attention in the spring.Perhaps an alternative here is a layer or two of very fine glass cloth over the stressed areas which are cracking bonded with epoxy. Don't forget to varnish on top of the epoxy to stop the ultra violet degradation. Its it a whole lot easier than re-decking and will add almost no weight. Done carefully you should still see the grain through the cloth. These are after all racing machines not furniture.

Striped back the starboard deck today and came up like new. Can't believe how lucky I have been so far.

The lifting old varnish made all look so much worse than it is.

So far this job is going really well.

So 

I have stripped both side decks and the foredeck to bare wood. Now long boarding them to get the best out of the wood, remove any marks from previous UV exposure...!

Cracks are no longer a worry, wood is in good nick.

Planning to use clear coat Durepox on the decks

Not given clear coat Durepox much consideration for the decks, will ponder this for BAU but using it in white & dark blue for the hull bottom with bright orange for the board (probably will repaint in white this year though).

Spraying?

It's being recommended by the lads I am sharing a workshop with. They know more than I do about this sort of thing.

Will do the hull and foils in Durepox too it gives an awesome finish. 

Andy where are you based? I would be very interested in checking out your boat and if you make it near Lymington gimme a shout and come see the work we are doing here.

Regarding spraying I am not sure, maybe...! Definitely the hull and foils.. But the inside I am not sure.

Based in Tavistock in Devon but might be up to your neck of the woods over the festive period. Funnily enough, just noticed a "lumpy" area on the garboard plank and chipped off the paint to find the planks / keel damp. Not sure where the water came from - more clearing back to do! Will also ponder whether Durepox needs a topcoat or not; it shouldn't do, but then why is the wood damp? Hey ho, guess what I am doing this winter!!

There are a few photos of BAU over the years on my Facebook page, if you can find me!!

Sorry to hear about the dampness Andy...

Will know more on my boat this week when I start stripping the exterior paint off.

Trust me I have plenty on.

Storm Cloud did that for no obvious reason when I owned it. It was the keel aft of the case and a little on the garboards.

Once fixed it never came back, and we never did find the source of ingress.

This is forward of the case in the keel and starboard garboard plank. No screws or holes or obvious cracks, but bubbles in an area of epoxy filler alerted me - a wooden boat with osmosis! There was glass & epoxy with probably three layers of epoxy paint on it, so it should have been more than sufficiently sealled. Oh well, paint off, dry out and try and find the leak.

Only been done for two seasons so should dry out OK. Might saturate it with eposeal this time too.

I just applied some durepox to the inside planks under where the inflatable bags will go just to see how it works... 

All the guys I am working with swear by it as a hard and water resistant finish that gives a really solid surface.

Hi all, I have read previous posts about deck ply cracking and lifting... what is the current advice... strip it back and epoxy it to death or sail it till it falls apart and re-deck?  My issues is mostly longitudinal crakc sin the top veneer on the side decks.

I dont think re-decking will gain you much. The loingitudinal cracks are very common. 
 
Very fine woven glass over the localised areas seems to be the treatment of choice. This should give a long term fix, there is always the risk of it coming back if you epoxy it and there is only 0.5mm of veneer to play with.
 
Looking back though this thread its interesting how wooden construction has changed. Most GPs are now built with either a herringbone pattern where the sapele stripes go inwards towards the bow or with rotary cut sapele giving a swirl rather than stripes. The herringbone pattern means you are working a much shorter veneer joint on the side deck. It runs diagonally instead of longitudinally so you are less likely to find them opening up. The swirl pattern must mean that you can arrange the veneer join directly across the deck - ive not looked closely as I didn't really think about it until just now! Possibly the rotary is just better quality - it is expensive.
 
I think we would have to "adjust" our expectation of what a modern wooden deck merlin looks like  to use either technique - Alex Jackson'sn river boat is decked in rotary and looks stunning.

This thread has resuscitated from a few years back - I see at that point I was thinking Heaven Sent would need re-decking but in fact after the last refurb from Chris & DH at DinghyTec the problems with the foredeck have more or less disappeared.  The issue was poor sealing on the underside, definitely worth checking as any boat with a wooden foredeck may well be over 20 years old now and could well not have been epoxy sealed from new.

The other problem is that even relatively new wooden boats are decked using cascamite as the glue - it doesn’t leave a glue line.

Andrew’s deck  was coming apart and I think the gunnels were all that was holding the foredeck ply in place! 

Glad it’s sorted it out now :)

I complained to the boatbuilder (Jon Turner) after the Tenby Champs in which various bits of the boat parted company.  Quite a bit was held together with Cascamite and the boat was then 18 years old.  I'd said something similar to Laurie Smart when I owned Elusive and he said he hadn't really thought the boats would still be around in 10 years' time let alone 20 or 30, still being sailed competitively

For what it's worth, on 2988 I used a craft knife to open up the cracks, and lift the outer veneer on either side where it wanted to come, then used a palette knife to squeegee in foaming PU glue along the crack, Plastic film over, wooden strip following the join & clamped at either end, little wedges pushed in as necessary to press the veneer down where it was lifted, When all set, peel off plastic film, sand & varnish. Done a few years ago & hasn't budged since, but the boat is kept indoors when not sailing.