Covering old GRP dinghy decks with ply, mostly for appearance's sake

[Greenheart]

I'm not sure how daft or reasonable this sounds. I've seen lots of slightly flexible decks aboard otherwise-sound, elderly GRP dinghies. Little cracks, lousy faded colour, all very tired-looking...

...now, companies like Robbins sell 8' x 4', 4mm ply, not vastly expensive, nor terribly heavy, and I'm thinking the whole deck area of these apologetic-looking old glassfibre boats could be visually rejuvenated by carefully cutting the ply to size and bonding it to the glassfibre, having prepared the latter to receive it.

Since it must follow the subtle curves of the GRP decks, I suppose thinner ply would be better...but how thin is it available? The Robbins "Tiger Elite" doesn't come any thinner than 4mm, which won't bend easily over a short radius.

Considering the underlying GRP has been strong enough for thirty or forty years, this isn't a vital structural issue. I'm not bothered about the dinghy gaining a few kilos, and I reckon the impression she'd give would be of a clean composite boat, rather than a distinctly sad plastic old-timer.

Any thoughts on ply-over-GRP? Thanks.

 

[Tranona]

Getting it to stick would be a problem. When ply is bonded onto decks as in the decorative teak finishes on AWBs it is vacuum bagged to apply even pressure while the adhesive cures. Getting that sort of even pressure on small complex shapes like a dinghy deck would not be easy. A foredeck might work with clamps all round the edges and concrete blocks on top. A more sensible alternative is to buy 2.6mm teak veneer which you can cut into strips and lay like a laid teak deck. Bed in Sikaflex and caulk the seams. Easier to do as you can deal with small areas at a time. Did the sugar scoop on my Bavaria in this way and the entire cockpit on my Eventide, although on ply rather than GRP but same principle.

Great way of using up all your spare time and not too demanding mentally so plenty of capacity left to dream while you are doing it!

 

[prv]

How would you do the edges of the ply? Just leave cut ends, showing off the laminations and demonstrating that it's not a composite boat but a GRP one that some amateur has inexplicably araldited sheets of ply onto? Or are you going to be milling up lots of hardwood edge beading, which will still look weird, albeit more professional, and take lots of time and effort?

My suggestion is to get your boat and go sailing. After the first season, if the decks really are very tatty, paint them or apply new gelcoat. Don't try to apply AWB "teak decks" to a 40 year old GRP dinghy.

Pete

 

[PCUK]

How about Dek-King faux teak? Easy to lay and would look fabulous but more expensive than 4mm ply.

 

[Bodach na mara]

Ply decks invariably suffer from weathering in my experience, no matter how carefully they are varnished. (I assume you would varnish rather than paint the ply.) In addition, the cut edges are difficult to seal to keep out moisture. It is a lot of work that you are proposing and it will not last long.

 

[Greenheart]

Sincere thanks to you, gentlemen. Tranona, that teak-veneer-strip sounds an excellent plan, easier than great sheets of ply which won't curve in two directions at once.

Pete, after observing so much of my dreaming, you know that a large proportion of my sailing enthusiasm comes from far-reaching retrospect - mornings of bright sun falling on teak decks, decades ago. I certainly plan to be sailing this season, but I allow myself to hope that she won't resemble a chilly old plastic bathtub.

You've read my mind, about the coaming/deck edging...I had indeed thought to add some attractive hardwood capping where ply meets glassfibre. I admit, it'd be lots of work in a very small cause...but given the horrid weather so far this year, there could easily be months in which to work, before I'll want to launch!

As to other criticisms...surely West Systems' epoxy, or similar, will seal ply-edges against weathering? It's meant for submersed parts - I'd hope it can cope with a life of rain, spray and sun.

My impression of Tek-Dek and other such finishes, is that they're hugely expensive, very heavy, and not particularly realistic. I'd gladly be proven wrong.

I'd even go for Treadmaster, but have you seen the prices? The one finish I really don't like is cold, clammy painted GRP...

 

[Lakesailor]

A rubbing strake at the edge would cover the ply edge. You don't want thicker than 3mm.

This was how i did my Heron, although it was a wooden boat.

​

 

[Greenheart]

Beautiful work, Lakesailor. Just what I was thinking of. I wondered about the rowlock-support too...(Good God, after hundreds of years rowing, I suddenly realised I don't know what that thing is called!)...

...I know it's heresy to fit rowlocks to a serious racing boat, but I'm a confirmed non-racer, so in spite of my taste for fast dinghies, I'll be interested to hear how any of you would go about fitting a really secure, ideally recessed rowlock-support, to a plain GRP side-deck, without compromising the deck's strength.

 

[Rossynant]

Yes, wood veneer is the material - solid wood not ply. Teak is not best here, unless it's to be a bare teak deck. Mahogany or other similar woods that can be soaked with epoxy well will also stick better; such may also be treated with thin, penetrating kind of epoxy (lots of new kind preparations that soak into wood, even water based epoxy, come to market) so in effect will make epoxy laminate over deck.
Convenient to use 3-5 mm thick (strips for decking effect up to 10mm but overkill in a dinghy). Possible to cover the deck with whole sheet if there is a way to press it down evenly, so important is to have thicker stiff material to put over, place for clamping or placing good weights; or even a vacuum can be used.

P.S If not epoxied on, strips may be laid in polyurethane adhesive, some more elastic kind, "seam caulking" made in same adhesive, this can be sanded flush. Heard good opinions about 'rubber-polyurethane' glues, but no experience.

 

[Greenheart]

Thanks for that thought...although vacuum-sealing will be a shade too much effort for my humble plan! That's a point: can hardwood veneer be applied in the rough outdoor conditions of a boatyard on a fine spring day? No requirement for a bone-dry, fixed-temperature, dust-free zone, I hope?

 

[PCUK]

What about just using veneer. Easy to work with and fairly cheap. Also any finish you like. If it is epoxy coated it won't wear out either.

 

[Greenheart]

What about just using veneer. Easy to work with and fairly cheap. Also any finish you like. If it is epoxy coated it won't wear out either.

Yes, that's now accepted and the core of my plan, thanks...assuming it's a decent veneer with a finish like real wood.

Anybody know about fitting the rowlock-support on a GRP deck? I'll want my dinghy to have a muscle-auxiliary.

 

[PCUK]

The veneer will be real wood! If you've no local supplier there are plenty of good places on Ebay.

 

[Rossynant]

The veneer will be real wood!

+1. Just wood, no preparations or ready put glue, as this may not be made for decking on GRP at sea

That's a point: can hardwood veneer be applied in the rough outdoor conditions of a boatyard on a fine spring day? No requirement for a bone-dry, fixed-temperature, dust-free zone, I hope?

For epoxy naturally conditions must be right, temperature is important and so is good clamping.

For not so good conditions - I'm not much experienced with modern polyurethane glues, and these are made in various formulas.
One part kinds actually are hardened with moisture and for some wood should be sprayed with water a bit first. Only not a 'foaming' kind... Temperature not so important, lower means longer time to set. Faster acting kinds need no clamping, just press initially to expell air and get the glue layer not to thick.

I used an "Universal Two-Part Polyurethane Adhesive" for wooden parquet, in not so ideal conditions quite contrary... works - so how this goes:
Surface should be reasonably dry (not necessarily bone-dry, relative humidity of wood and substrate less than 70% ) free of oils, swept of most loose dirt; no old (not adhering) paints, glues and such. Temperature 10-30 C (done in about 5 C actually, was setting bit slow). Required to be mixed together, poured over the surface, wood put on (before it sets, up to 30 minutes) and pressed down. This was flat surface (concrete) and 15 mm thick parquet - was not necessary to keep it pressed really, but is recommended to keep pressure (weights) for a while, as glue hold initially is not so strong. This kind adhesive is water resistant, frost resistant, holds onto wood well (on removing wood breaks, not glue), elastic; they say acts on GRP. It glues to everything probably.

 

[Lakesailor]

Yes, that's now accepted and the core of my plan, thanks...assuming it's a decent veneer with a finish like real wood.

Anybody know about fitting the rowlock-support on a GRP deck? I'll want my dinghy to have a muscle-auxiliary.

Interesting thread on your point on the Wayferer site http://www.wayfarer.org.uk/forum/viewtopic.php?f=5&t=1202

BTW: If you use epoxy to bond the wood to the grp mechanically abrade the grp first and coat both surfaces (the wood will absorb a lot of the epoxy, so use a thinner mix on there. I use a slow cure, thin epoxy for coatings and bulk it up with wood dust for areas needing a thicker mix.) Once bonded, the wood will fail before the epoxy does.

 

[Greenheart]

Thanks, Lakesailor. Very busy now, but I'll read it soon.

 

[TSB240]

Why not just wrap it in vinyl........

Modern high tech Carbon fibre effect deck.....

Or if you hark for the ancient wooden deck effect

Both easily added

Minimal weight

No need for finishing trims.

http://www.wildgroupinternational.com/Why-Vinyl-Wrap.

FABLON would be cheaper

 

[Lakesailor]

Why not just wrap it in vinyl........

Modern high tech Carbon fibre effect deck.....

There is a guy with a Sporting Trials car who has wrapped it in carbon fibre effect vinyl. However his firm does vinyl wraps.

 

[lw395]

Some grp decks are quite 3D so might not be easy to do neatly.
Also the gunwhales tend to be very curved on many boats, and if there is a breakwater on the foredeck, that would need careful work not to look odd.
Although you may have zero interest in racing, think carefully before taking a boat irretrievably out of class, as it reduces your options of people to sell it too.
There are many boats out there with a wooden foredeck already, I used to have an old 505 with just the foredeck in wood.
Revamping a boat like that could be a cheap way to a nice looking boat.
Some boats are better smartened up with some stick-on non slip like 'progrip' and enjoyed on the water.

We want to hear you've bought a boat before too long, Dan, the season is nearly upon us.
Are you any closer to deciding what you want?

 

[Greenheart]

Why not just wrap it in vinyl........modern high tech Carbon fibre effect deck.....no need for finishing trims...FABLON would be cheaper

Hmm. My hope was to reduce the nasty harsh plastic look & feel...so real wood is preferable, although I'd consider something like Treadmaster or Progrip, which somehow turn unashamed artificiality of material into a warmish, slightly cushioned finish.

My question was for aesthetic & comfort reasons, so I really don't want a boat decked in carbon-fibre or duralumin alloy, or some weird campy spandex, nor do I want it to resemble a glossy-golden 1970s veneered sideboard - eek! - if it was possible, I'd like an unvarnished deck in plain teak, though whether such a finish is available in veneer, I really don't know.

Think carefully before taking a boat irretrievably out of class, as it reduces your options of people to sell it to.
We want to hear you've bought a boat before too long, Dan, the season is nearly upon us. Are you any closer to deciding what you want?

Thank you LW395, I know that's good advice. I'd hope only to make changes to the feel and appearance of the boat; but I recognise that adding a layer of something like Tek-Dek might easily increase hull weight by 20kg, which won't then appeal to even the humblest club-racer if I wanted to sell the boat on.

On the buying front, I can say (without promising anything I can't fulfil) that I won't leave this forum breathless in anticipation for very much longer...

...I will be sailing a GRP dinghy this year. She'll be ancient, riddled with faults and imperfections, so I'll be gratefully devouring advice from the forum all year long.