Thread: GIS for the former small-dinghy sailor

Hah! Try to get quarter-sawn anything - or even at an affordable price - except by chance, and you're in for a hard time! Or at least, that's been my experience in recent times.

I've ordered some Paulownia from Whitewood per nickpullen's recommendation. John was particularly helpful and bent over backwards to help.

Michael made some warning remarks about spruce in Oz in the instructions for the PDR or the GIS (or both?), and the cost of getting decent stuff would most likely be worse that good oregon. I haven't even tried, I must confess. Hoop pine also seems to be quite hard to find, at least in the vicinity.

Speaking of oregon, I picked up a few bits and pieces from the local timber yard on the weekend, and will be able to use a bit for the Duck and a bit for the Goat, with some judicious machining and probably scarfing. Nice fine grain in some of it, with not too many "knotlets". But the majority that I looked at in the yard was full of quite large knots, so avoided it like the plague.

At the risk of twisting this thread, I think the Paulwonia will mostly go into the PDR, which I got the plans for at the same time as the Goat. I'd prefer to make the Goat first, but a. I won't be able to afford six sheets of 6 mm gaboon, not to mention the tanker-load of epoxy, plus the sails, for some time yet (previous mid-year start estimate is looking shaky!) and b. I want to get sailing relatively quickly (see also a. above ;).

I say *relatively*, as The Boss has got wind of the scale of the project (well, both of them) and is making me luff into the wind, so to speak. Unless I flange up a quick-and-dirty balsa model of the Goat and sail it from the bank under r/c :). Or whack wome rowlocks in the Duck and go paddling about (but that's hardly sailing).

Still, a bit here and a bit there: and I am still collecting clamps. Fortunately have most of the other wood-working tools already.

Whilst browsing around on BoatCraft's site, I found their "Timber Preservative Additive" (TPA), a.k.a.(?) "Timber Preservative and Reactive Diluent" (TPRDA), which is added to the mixture to improve the penetration of the 'pox into the timber, plus adds a fungistat, which is all fair and good, etc.

It sounds very useful in principle, BUT: is this in fact going to increase the weight of the boat with the increased uptake of resin in the first coat? Or will the actual extra amount be marginal, given that a. the 'pox is diluted and b. the diluent will have evaporated (unless it eventually cross-links and stays put)? Presumably uptake will stop when it hits the first glue layer in the outer plies in any case.

Thoughts on this will be gratefully heeded - I don't want to end up with a Goat (or PDR) weighing a ton! Or make a mountain out of a molehill ;).

I just emailed BoatCraft (Qld) to find out their opinion on the above query...

Howdy Alex,

It is a nice product ... but not necessary at all for when new materials are being used. I think there is little justification.

If good woodworking epoxy is good as a glue in its unthinned state (you NEVER thin epoxy glue mix with solvents of any type) then I can't see why it needs to be diluted to "improve adhesion". This is a hangover from using polyester resin which does not stick to wood very well at all and cannot be used as a woodglue effectively and thinning with acetone on the first coat can help a little.

You should not use the TPRDA it for anything structural like gluing or glassing, but where coating a degraded surface it can help get the epoxy in a bit deeper to consolidate the existing structure.

However if the rot or damage has penetrated more deeply into structural parts then the part should be replaced or reinforced.

Best wishes
Michael.

Thanks MIK :). As the ply is going to be 100 % "new", then I'll forget about using TPRDA.

I'll be using BoteCote anyway, since it doesn't need dewaxing, so that sorts another problem (well, several in one fell swoop :). You will no doubt be relieved to read that I wasn't going to add TPRDA to the glue, only to the inital ply waterproofing coating, with gluing areas masked! (Note also that I've taken on board your comment about WEST's advice about primary & secondary epoxy bonds.) And I hate polyester resin! I will go to great lenghts to avoid it, which is why my model aircraft cowls are all made of lightweight GRE.

I'll keep the advice in mind in case I have the boat long enough for it to have a chance for the rot to set in (but see also above :). Unless the ply arrives already rotting - in which case it will Go Straight Back(tm). I am unhappily getting quite good at sending duff mechandise back...

Cheers,
Alex.

OK, I've been ringing around regarding sources of gaboon that I don't have to pay huge freight charges on, and have been alerted to a ply called "Eurolite", a.k.a. "caravan" ply, made from Italian poplar, apparently: there is a link on this page to a pdf of info on the stuff.

From this and other results of Googling, it looks as though it's going to be too flimsy for my purposes (even for a Duck, let alone a Goat), and could be stuff that one could put their foot through if not careful.

Has anyone had any experience of this ply, first-, second- or third-hand?

Cheers,
Alex.

One major step forward today - the paulwonia arrived this afternoon. Gee, it's light - and soft! It's harder than balsa, though, and seems almost as light. I can see why it's used in surfboards.

When I put the order through, I also accidentally put in for bits for the mast - oops! After discussing with MIK, I decided to use the paulownia in the lug rig for the PDR, not the GIS(!), and glass it up. A back-of-the-envelope calculation suggests around 20 % of the weight of the wood in glass to bring it up to an oregon-like specific gravity of 0.3. With an approximate weight for the mast of 3 kg without glue (based on a quick use of the bathroom scales), this equates to approx 600 g of glass. For 1.25 m^2 approx. total glass area incl. overlaps, the weight of the cloth comes out at 480 gsm. Perhaps this could be lowered to 285 or thereabouts, given the large amount of resin that this weight (285) cloth is going to suck up. Plus the mast step and partner will have to be reamed out accordingly to account for the increase in mast diameter caused by the heavy cloth. An interesting experiment, at any rate.

I think this wood may also be going to hoover up the resin, so will do some tests on small lengths to see what it actually does. It may in fact be so thirsty that the lack of weight of the wood will be made back up in increased resin consumption.

Then again, this will probably add to strength, if the fibres in the wood are of sufficient length in relation to the thickness of the boards. So far the feel flexible enough without being too whippy. I've still got some WEST 5:1 105/205 (fast hardener), which will be useful for an initial test, before I get the 1:1 BoteCote (and high-strength powder - already have a big box of Q-Cels which I use for aircraft wing fillets, works a treat).

Used carefully (i.e., not in high-traffic areas) I've probably got enough paulownia for three boats (I'd add a Raid41 to the list but I wouldn't have room to store it!).

Also found some clear-grained oregon kicking about in my wood store, once I got the paint off - it's at least 10 years old, scrounged from the tip. Only trouble is that it's (a bit!) too short to use for booms/sprits/yards: I wouldn't trust scarf joints on those bits. And also too short to move the scarfs sufficiently far apart for use in mast staves.

Back to ply searching...

Fun & games :).

Cheers,
Alex.

One more thing about the paulownia - John from Whitewood Timber did a fantastic job milling it all - all square, no milling marks to be seen, and a resultant finish that you could almost use as a mirror. Well, perhaps not quite that smooth, but pretty jolly good. Very finely crafted, and you don't often see that in milled timber (or at least, I don't).

Alex.

You should be able to find gaboon ply in Sydney fairly easily. Look in the Yellow Pages either for someone like Mr Ply and Wood or for the item 'plywood' in a suburb like Brookvale and you should get someone closeby who stocks it.

Hi Theodor, thanks for the suggestion. MrP&W can't get any gaboon in (suppliers don't have it), one place in Brookvale doesn't stock imperial sized sheets in marine of any sort, and another one in B'vale is a *lot* more expensive than BoatCraft in Sydney (Drive Marine Services) or Qld, even with freight added. A number of other places that I've rung in Sydney are also out of stock.

I am still curious about the "Eurolite". Anyone? Maybe I'll forge ahead and experiment with it anyway.

Cheers,
Alex.

Originally Posted by AlexN

I've still got some WEST 5:1 105/205 (fast hardener), which will be useful for an initial test, before I get the 1:1 BoteCote

Idiot! BoteCote is 2:1!

Given that the actual use of the "Eurolite" will be for my PDR bottom, NOT on (under) my Goat, perhaps I'd better post the query in one of the PDR threads. I'm assuming for the sake of argument at the moment that noone else has used the stuff, and proceeding accordingly.

Given the apparent quantities of gaboon that almost all of the suppliers that I've contacted in three States don't have, I'm going to be having some fun when I get around to ordering in the ply for the Goat! Maybe it would be better to order one or two pieces at a time where available.

Experiments on the Paulownia this weekend. I may even post some pictures if it looks worthwhile and there is any interest...

Cheers,
Alex.

It is too soft for places where it will be bumped, but seems OK for cleating in low stress structures like the Goat and PDRacer.

Parts that may be bumped should be something heavier - gunwales, bottom runners things like that.

MIK

I'll be saving up for the Goat ingredients :). Hopefully I won't have to go through the conniptions that I've so far been performing wrt the Duck parts! A piece here, a piece there...

The WRC (internal) cladding that I have been intending to use is 10 mm thick t&g-ed boards, 75 mm usable width, cut up into strips to go into foils for both the PDR and the Goat. Would the increased number of laminations (i.e., 3 times the original number) hurt the end result, given that the glue will be eopxy+Q-cels?

I've given a piece of Paulownia a quick coat of WEST 105/205, to see if the wood soaks it up. So far it doesn't seem to have go in very far on the sides of the piece; the end grain a bit more. Not as much soaking in on any surface than I was expecting, though. Once I get the BoteCote that I ordered last week, I'll try that and see what the difference will be.

Most of the Paulownia will go as "hidden" structural items in the PDR (plus the glassed lug mast per previous discussion), with the remainder to in the Goat in similar spots (not the mast though!).

Cheers,
Alex.

Howdy Alex,

The idea that the epoxy "soaked in" in some sort of special way was an error from the early days.

We know that it usually doesn't soak in a long distance but is very effective nonetheless.

However there is lots of chatting on the net by people trying to make it soak in more ... they are mistaken. Almost every method used to achieve that end reduces the strength of the join. The epoxy needs to be undiluted to glue well ... so why there is a mistaken idea that it needs to be thinned when coating only ... doesn't make any sense at all.

MIK