Choice of Plywood

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NicM

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My first post on the forum so I hope this is the right section.

I am about to start building a Highlander 18 from Selway Fisher. I've got the study plans and I am sorting out the shed. One of the MANY things that is confusing me as a first time builder is the choice of plywood.

Many people use 'ordinary' wbp or external plywood and swear by it whilst books advise the use of BS1088 (hope that right).

Also there is a huge range in prices for BS1088 surely if it is BS rated one 6mm sheet should be as good as another /forums/images/graemlins/confused.gif
 
My advise to you would be to look very carefully before you buy. I saw some absolute garbage bought , cheaply it has to be said, as marine ply last weekend. One full sheet was full of gaps in the core layers and the face veneer was so thin it had no observable thickness. I reckon if you took a sheet of sand paper within a 100 metres of it you'd have been through it.

A local boat yard wanted more for a 2ft square of what was presumably decent quality stuff than whole sheets of this stuff cost from a well known timber merchants.

I assume what you are building has a ply hull so for the hull, deck, superstructure etc get the best you can find. Economise if you must on the interior joinery.
 
The rating of BS1088 refers to the minimisation of voids in the laminate and the quality of the glued joints. The higher price marine plys tend to be made from better gardes of timber.

The danger of WBP is that it is not certified to be free of internal voids, such as the places where knots have fallen out of the laminate, or the edges of the laminate do not meet precisely. This may result in weak spots and places where moisture can accumulate and therefore start softening the ply.

As mentioned, if it is somewhere that is likely to be wet all the time, go for BS1088 minimum, and consider one of the more expensive grades from somewhere like Robbins timber. For other areas that may get wet, but not permantly, WBP should be OK.

I only use BS1088 on board, but usually use the cheaper(est) grades for internal fit out and a mid range ones for exterior above water regions, like the deck.
 
I made some washboards out of WBP, with several coats of varnish. After a year, the layers were separating, mouldy, stained, and generally manky.

We will use them as winter ones to keep the (marine ply) ones for the summer.

In other words, wbp is not suitable for exterior use.
 
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Highlander 18 from Selway Fisher.

[/ QUOTE ]

Nice boat!

Just my opinion (click my sig for pictures) but based on building a 17' power boat your wood is going to be a relatively small cost of the overall build, so get the best you can.

All my wood came from Robbins Timber in Bristol, delivered by them to Surrey. 25 sheets in total, and no voids found.
 
I built a 12' dinghy using mostly exterior ply from a local builders merchant, but marine ply for the bulkheads. In the end I wished that I'd used marine ply throughout. When compared with the total cost of the project the difference wouldn't have been that big. However the marine ply was fantastic to work with compared with the other stuff.

I have since built a couple of canoes using Robbins Elite ply. That was really good to work with too.
 
As others have said, 1088 refers to voids and adhesive. It does not set a standard for the material of the laminates. You will find a huge difference in quality ot the wood and the number of laminates. I have use 1088 as a temporary sole and the wood rotted.

Try to find a merchant you can trust and throw yourself on his mercy.
 
We buy a lot of ply every year of different qualities and there is a huge price difference across the board (pardon the pun) depending on whether the wholesalers have done any deals, so it pays to shop around, it does not necessarily mean 'its cheap' therefore its no good, but you generally get what you pay for. The best prices will be from the guys with the higher throughput.
If the boat is NOT going to be afloat all the time, you could build the hull from WBP ply, afterall it is an external grade designed to get wet, with 2 coats of epoxy each side it will only enhance its performance, but I would bite the bullet if I were you and use Marine for the hull and WBP for the internals, unless money is very tight.
 
At a friendly neighbourhood DIY store, where short sheets of WBP can be purchased (1/2 & 1/4 size), I went through their entire stock without finding a single piece that had not started delaminating. Use marine ply for boaty things.
 
Wish you luck with the build. I have just recently completed a Highlander 18 myself. Unfortunately work butted in before I could get the masts and rigging sorted out, so its been lying on the trailer at the back of the house (never been in the water yet).

Couple of thoughts. Ive built 3 boats now and the highlander construction was the most difficult to get my head round. In future I will stick with traditional frames and boards.

As far as plywood goes, stick with BS 1088. If you are going to cover with glass and epoxy, standard stuff from Jewson or where ever will be fine. If you are not using epoxy go for the better stuff Brunzeel etc see Robbins web site.

Oh and if you fancy one ready built, mines going for a song with a brand new trailer.

Cheers

Colin
 
Mostly said now, I used occume sourced from a good supplier, not 1088. But no voids, clear surfaced laminates of good thickness. Very happy. If you don´t know what you are looking at, buy from Robbins, it is good. On the construction, get Iain Oughtred´s book, helpfull for any ply build. There are also other `Stich & Glue´books out there, check Watercrafts
lists (sorry YBW) You might also look at The Wooden Boat Forums. Lots of v. expierienced people there. Good search engine too.....
Andrew
 
[ QUOTE ]
Just a quick search on Google tonight found these

http://www.kjhowells.com/hardwoods_plywoods.html

who are less than half Robbins and many in between so you can see my confusion.

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Be careful, looking at the prices, the only 'high risk' (whatever that means) seems very expensive. I didn't pay anywhere near that for the Robbin's stuff. I don't know what they mean by 'low risk' and I'm not too sure of the Far Eastern tag that goes with it.

As a previous poster mentioned, the Robbin's ply is a joy to work with. Easy to cut, sand, coat etc., and will make you turn your nose up at any plywood you ever see in the hardware stores.

Just my opinion... /forums/images/graemlins/wink.gif

Oh, and you're right, you can NEVER have too many clamps!!!!! (you must have seen this one earlier...)

DSC_4401%20Rub%20rail.jpg
 
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