BS1088 vs Robbins...

[Kelpie]

Next year we hope to set off for a few years of bluewater cruising. I've had enough of floppy inflatable dinghies and want something with more rigidity that will survive scrapes and bashes, and be better under both oar and motor. The usual answer would be a RIB but as our yacht has a babystay bisecting the foredeck we don't quite have enough space.

So we have settled upon the idea of building a stitch and glue nesting dinghy from plywood, and have chosen the Spindrift 11N design from B and B boats. A big advantage over a RIB will be that we can add a sailing rig.

This will be very much a utility boat, used daily, and does not need to be pretty. I would like to keep it as light as is reasonably possible, and for the effort that will go in to building it I would want it to last a few years at least.

The choice of plywood will make a massive difference to the overall project cost. Standard 'marine' ply from a builders merchant would chop nearly 40% off my total materials cost, compared with Robbins Elite. That cost saving would allow me to sheathe the whole boat if necessary, although that would obviously add weight.

Any suggestions on which way to go with this? Has anybody here built a boat from cheaper ply and if so, how long did it last? My gut feeling is to find the extra cash and go with Robbins, I know we will not regret it, but as our leaving date approaches the dinghy is not the only thing we have to spend money on, and we need to make some careful choices with our budget.

 

[PeterV]

I've used Marine ply from a builder's merchants and Robbins Elite for several jobs. The builders merchant ply has always had large voids and even overlapping veneers. The strength is very weak and the structures have failed very quickly. Robbins Elite has been much stronger and is lasting after 10 years. You will probably find that the epoxy and glass costs more than you expect and the cost will be completely wasted when the wood fails.

 

[Deleted member 36384]

Robins stand by their product and actively manage the quality of the supplies they get in the marine ply space. Unlike PeterV I bough a sheet of Elite and more than a year later, after cutting bits off it, I cut into a long void. Robin's could not have been more supportive. I took a picture emailed it to them, cut out a section and posted that to them. The next day, by recorded delivery a whole new sheet arrived, un asked for. They sent the failed part to the manufacturer. In the decided dicy world of marine ply, you can trust Robins and their products. I have bought a few sheets from them, Elite and the not Elite brands and this is the only issue I have ever had.

It's difficult to say about your needs, a good exterior ply should last a long time if stitched and glued, plus all edges given a good sealing. For what your proposing I would put the effort into sourcing a good exterior ply.

 

[burgundyben]

After 20 years of plywood boats...

My rule of thumb is that if its going to be glued and screwed to the boat, deck, bulkhead or cabin roof as examples then I use Robbins elite.

If its a door or locker lid then 1088 from the builders merchant will do.

I would use Robbins for a dinghy.

 

[Keith 66]

Today you rarely rely on any plywood from a builders merchant whatever is stamped on it, I have seen plywood with Exterior or Marine with BS 1088 stamped on it that failed within days when it got wet.
Anything from the far east is suspect & much of it appears to be stuck together with wallpaper paste.

 

[oldharry]

+1 In the last 10 years or so the BS mark has meant little more than Bull Sh*t, uness it carries the true BS mark. Even if it does, it may not be genuine, having some minor difference from the true British Standards Marking. The comon excuse it being its a stock or catalogure number. True marine ply must have all sheets the same timber and thickness, and proper marine glue. Nearly all Builders BullSh*t1088 has thin decorative veneer over softwood cores with rubbish glue. True BS1088 also has a maximum number and width of voids betwen internal veneers.

Builders 'marine ply' is rarely suitable for structural use. I used some for an internal engine casing which only occasionally gets splahed, but even so after a few years the veneers are seperating.

 

[guardian]

+1 In the last 10 years or so the BS mark has meant little more than Bull Sh*t, uness it carries the true BS mark. Even if it does, it may not be genuine, having some minor difference from the true British Standards Marking. The comon excuse it being its a stock or catalogure number. True marine ply must have all sheets the same timber and thickness, and proper marine glue. Nearly all Builders BullSh*t1088 has thin decorative veneer over softwood cores with rubbish glue. True BS1088 also has a maximum number and width of voids betwen internal veneers.

Builders 'marine ply' is rarely suitable for structural use. I used some for an internal engine casing which only occasionally gets splahed, but even so after a few years the veneers are seperating.

Travis Perkins are the guilty ones in this, had a job to do a while back and told the customer to buy Marine Ply (BS1088 etc) and got what can only be described as WBP with a BS1088 kite mark such was the poor quality. It was every bit as bad as the WBP crap now sold in merchants but cost 3 times as much according to the customer. In my experience as a joiner even when it has the BS1088 kite mark it still means nothing. Another industry ruined ruined by market forces.

Heres a sheet of kite-marked marine ply i cut through whilst converting my work van a few years back: