Thread: GIS for the former small-dinghy sailor

BOOKSHELVES ... start building a PDRacer and she may not twig until you starting making the sail!

Just printing the "bookshelf" instructions at the moment, in fact, having read through 0.75 of the GIS instructions. I'm going to have to re-read them a couple of times, as although the boat has relatively few parts, there does seem to a lot of planning involved, especially with glue.

There also appears to be a lot of very careful work with a plane needed - and planes are particularly what I am not best with! So I am going to have to do a lot of practice on ply in hand with my block plane, while I scour the world for a second hand jack plane ;).

I think I'll start with the "bookshelves" as practice, and maybe do up a 1/4 - 1/5 scale model of the GIS in mousetrap ply, before I commit to marine gaboon. The gunwwale/inwale system and the mast are the parts that are going to test me.

I will compile a list of questions to email you per the suggestion in the GIS booklet - unless it would better for all concerned to post them here.

Cheers,
Alex.

Howdy Alex,

The plans do lead you up to the point where putting the glue on will be fairly foolproof.

I am very careful to cover all the steps that need to happen prior to those points and keep the glue well out of the discussion so the builder can get on with the dry process.

Then they can already see how things fit together when that stage of gluing arrives.

So just follow the plan through ... it will help you set up everything ready for each gluing stage and mostly eliminate the chances of error because of the careful preparation for each step.

Some more experienced builders will be able to see shortcuts - not many - because I tend to take a pretty direct route through the building process, but they might be able to save on some of the double checks before assembly .... because they know the purpose of the checks.

Best wishes
Michael

Hello Michael,

Thanks for the advice.

I am going to have a bit of time studying the instructions while I get the workshop cleaned up and I've saved up for the wood. I've just spent equivalent of the cost of the ply for the for two GIS-es on a decent drill press :(. Its already quite expensive predecessor had be returned under warranty having come with a bent spindle. Most of the drilling that I do is in metal in preparation for milling and lathework, where my tolerances are around 0.01 mm (or less).

The queries that I have at the moment are peripheral rather than procedural:

could jarrah be used for the skids;

could Aust. red cedar (or jarrah) be used for the capping on the bow;

how many (spring) clamps should be considered a bare minimum for doing the gunwales/inwales? Tape-wrapping isn't an option here, and I don't want to go crazy with screws. I counted 56 clamps on one side in the 2007 Spring School photos! Maybe I can find somewhere that sells them for <= $1 each.

Cheers,
Alex.

I believe I had a couple dozen spring clamps while working on the inwales. I supplemented them with a few bar clamps large and small.



I didn't need many clamps for the out-wale--I screwed it in place after first laying out the inner blocking. Knowing where each block was to be I put the screws in where the blocks would cover the holes at the next stage. I can't recall the procedure for installing the out-most rub strip. Oh, yes, I used the spring clamps. They are too small to reach across the whole assembly but you've got the gaps between the blocking and the medium clamps will reach that.

BTW--if you're using the coarse thread drywall screws MIK recommends you don't need to drill pilot holes in most cases--through plywood and into soft lumber. If you use a small piece of ply for a washer the marks left behind when you pull the screws will be tiny.

Re: the sequencing of epoxy coating and glue-up. MIK's detailed instructions cover that very well but after considering the time requirements to complete some of the processes I finally concluded I could not pre-coat parts in the flat before assembly because it requires a lot of time to stay on task from start to finish. Unable to set aside enough time, I had to adopt a different strategy and do the epoxy sealing after assembly--the centercase being the only exception. The thing you want to avoid if possible is assembling pre-sealed surfaces where the epoxy is fully cured. The strongest bonds are obtained by either gluing bare wood to bare or pre-coated pieces while the epoxy is still green....I think. Someone please correct me if this is wrong.

MAM is absolutely right in describing the two types of bonds: secondary and primary (chemical). It is much stronger to saturate the wood with resin and apply thickened epoxy and glue together getting excellent squeeze out than it is to coat two surfaces, let cure, sand, then glue together. The latter is developing a secondary bond, the former a primary bond. But it is also true that the sequence of events needs to be put into a timeline and adhered to, everything is time dependent. If something comes up and you can't get into the shop to do a glue up before the precoated wood is cure, then you'll have to live with a secondary bond. It is still strong, mind you, particularly if the cured surface is well sanded and an 80 grit is uses to pep the "faying surface". Now, having hardeners of different rates of cure, fast, medium, slow can be a big advantage as can controlling the temperature of the shop.

Cheers,
Clint

Hi MAM,

Thanks for your pic and advice. I guess that the vast array of clamps on the DF GIS was because, being professional boat-builders, they had vast numbers of (predominantly spring) clamps in hand already!

Thinking more about your pic, those from the DF school, and the plan view of the boat itself, the amount of clamping is partly going to be determined by the amount of curvature and the flexibility of the timber (i.e., the tighter the curve the more clamping needed).

The cheapest price I've found for spring clamps so far is AU$3.00 each, so I could plan to buy a few at a time over the period between now and when I start building (probably mid-year), which would spread the cost out a bit.

Re using the bugle-head plasterboard screws per the plans and your advice, I still want to limit the number of screw holes, but will have to balance that against the overall cost of the boat.

Then again, the clamps will always be there for another project (e.g., building another boat ;).

Cheers,
Alex.

Hi Clint,

Thanks for the points about gluing - the staging is what I meant (and have reinforced in my own mind) regarding the amount of planning required to build the GIS (and the PDR for that matter). And is why I will be reading the instructions a number of times before I decide which way to go - ultra-waterproof, or easier ;). The comment about the relative strengths of the bond types also reflects my own preliminary thinking - it's nice to know that I occasionally get onto the right track :).

Cheers,
Alex.

Noticed Bunnings have 4-packs of ratchet clamps on special this week for about $10.
2 x 300mm & 2 x 160mm or thereabouts.

cheers
AJ

Thanks, AJ! I just had a sqizz at their online catalogue. They look useful if they're not just cheap rubbish (I'm still twitching over the *not cheap* drill press episode, grrr). I'll nip down (to Thornleigh, not Mile End ;) and have a look tomorrow.

Cheers,
Alex.

Thanks, AJ! I'll nip down (to Thornleigh, not Mile End ;) and have a look.

Cheers,
Alex.

Originally Posted by AlexN

Thanks, AJ! I just had a sqizz at their online catalogue. They look useful if they're not just cheap rubbish (I'm still twitching over the *not cheap* drill press episode, grrr). I'll nip down (to Thornleigh, not Mile End and have a look tomorrow.
Cheers,
Alex.

I'm quite sure they are just cheap rubbish! On the other hand, they only have to do a
simple job passably well, & if every 4th one is a dud, they're still cheap.

Now, how did you know I went to Mile End, not Oaklands or Noarlunga ???

Well, I'm back from my trip to Bunnings. There were only 1.75 sets the 0.75 set had one of the large ones missing, so it either got ripped off or (more likely) broke in use and was returned ;). So maybe that was the 4th one :).

Anyway, I got $4.00 off for that, which is better than a poke in the eye with a sharp stick. I got both sets. They do look like cheap rubbish and probably not up to the rigours of building the GIS, but they will do for some of my larger scale aircraft (and won't damage the balsa too much).

What I did find, however, were bags of plastic spring clamps, 16 per bag, in 5 sizes (4+4+4+2+2, smallest to largest) for $10/bag. These are more promising - I got two bags. From now on I think I'll get the $3.00 ones from McJing, though. And save up for some more Bessey clamps.

Spooky, wasn't it? I can read your mind ;). Nah, it was the one that I went to when I lived in Adelaide - when it was Harry's then BBC. It became Bunnings a while after we left. I've seen it in its new livery on occasions that I've come home for a visit.

Cheers,
Alex.