Thread: Goat Island Skiff building in Denmark :-) Sejl-jolle bygges i Danmark

Hey David!

The driftboats are a good point. I do tend to think the idea of graphite/epoxy coated bottoms is rubbish (note ... this is my BIAS ... I have zero evidence.

I can cancel out the claim for low drag (as I did above) ... it just cannot work. Where ppl tout one wrong idea without evidence there is a good chance that their others MAY be of a similar ilk.

BUT .... just had the thought ... fast flowing rivers will mean the stones are rounded?

There may be some chance that a graphite bottom sliding across a smooth rounded stone might get some lubricating effect.

Stream of consciousness here ... I was about to argue that the graphite may have some useful effect but then thought ... but if is is possible to SAND the graphite, rather than the sandpaper slide across the surface uselessly then the rocks will do the same thing.

Make up some graphite and see if it does sand easily enough.

.... thinking more ...

OK ... actually already done ... WEST pioneerd the method of laying teak veneer decks in simulated planking by laying it in graphite/epoxy mix. They let it ooze then sand the lot after. They have done it on very large boats so if it was hard to sand then it would be a useless material for that method

So you can sand the graphite/epoxy easily enough .. so I think the graphite is VERY unlikely to work.

Easy to do a test or two though! Make a panel up half normal epoxy coats, half graphite epoxy.

1/ try to sand both with different grade papers. There needs to be a significant difference for it to make a difference when skidding across a rock.

2/ put a couple of drywall screws near the end of a medium weight bit of wood and drag the points across both surfaces. There needs to be a gross easily sensed difference here too.

You can probably guess that the sloppy experimentation and scientific ignorance of Mythbusters drives me crazy!!!!

I'd be reckoning that the real advantage is that the drift boat guys are just happy not touching up paint after every trip; and claiming other benefits is because they love the idea so much!!!

Best wishes
MIK

okay, Mik, you have convinced me not to be the first one to check that out
I'll stick to your plan.
Is there any benefit in 'fibre the inside of the centercase ?

btw, Mythbusters is great - dont know about that science, but it sure is pure entertainment

Bjarne

Howdy Bjarne,

If you want you can put some glass inside the centrecase. Keep the glass away from the areas where the timber is going to glue.

Best wishes
Michael
(did you see the new thread about Jason's blue GIS)

Sounds good, i think im gonna use som glass then
And yes, i have seen hes boat - its nice. I also like the blue color, but i prefer white

Tomorrow its glue time

Bjarne

I'm a little confused, im in the progress of placing the Bulkheads. But i can't find out where they are placed. I'll try to explain what i mean.

If you look at the picture named boatmik.jpg you can see i have drawen BHD 1 to 4 on the image. And if you look at the picture Drawing.BHD.jpg i have done the same.
But what confuses me is that on the image from Mikael is that BHD #2 and BHD #3 is very close to eachother, but if you look at the drawing_bhd.jpg is the BHD #3 and BHD #4 very close to eachother, which i dont understand.
I have been looking at several pictures that all seems to be the same as in Mik's boat. There is obvious something i have misinterpret, but what ?

[media]http://farm4.static.flickr.com/3260/2810784890_5540ae88e9_b.jpg[/media]
[media]http://farm4.static.flickr.com/3216/2762514930_7d85103397_o.jpg[/media]
[media]http://farm3.static.flickr.com/2133/1503720547_edc5261169_o.jpg[/media]

Bjarne

Always good to check Bjarne!

The bulkhead that you have labelled at number 1 is actually number 2. You cannot see number 1 because it is hidden under the front seat.

At the middle seat there is only one bulkhead in the plan and you have two labelled. It is located at the rear edge of the seat.

Hope this helps
Michael

'morning (atleast from a Danner point of view, its 7:30 here )

That solved one of my concern. The other one is that i'm kinda dum - i were looking at the front and reading it for being the stern
A good reason not to work when you are tired and got a headache

One other thing, is it possible to buy the dagger-board and the ruder ??
I'm pretty sure thoose two thing is out of my league.

Bjarne

Originally Posted by Maximuss

One other thing, is it possible to buy the dagger-board and the ruder ??
I'm pretty sure thoose two thing is out of my league.
Bjarne

I reckon you'll be surprised how easy it is Bjarne.
The foils work best if they are perfect.
They will still work if not perfect.
The template MIK supplies makes it easy to get very close to perfect.
Just clamp your board firmly to a flat, straight surface, & keep wearing down the
high spots as per Michael's directions.
Practice on a spare length of timber or ply off-cuts.
cheers
Alan J

Hi Bjarne,

they are two or three hours of work. If you found a second hand rudder and centreboard for the LASER they will fit Ok, but you need to make the centreboard case a little wider to match the Laser centreboard.

You will lost a bit of performance but the boat will still go pretty good.

Did you see the way the template works for shaping the GIS centreboard and rudder blade? It is pretty simple.

You can see on the OZ PDRacer site
Making Accurate Centreboard and Rudder Blades/Foils



MIK

Well, it look easy but i'm not sure if i'm good enough to do it anyway - but if all kind of woods can be used i think i will try. We have a discount shop with some cheap wood, its not worth much but i can try it first.

Bjarne

Glue them up out of narrower width timber maybe 50mm wide. Don't use wide planks. And you can use any waterproof glue including some of the convenient water based ones.

Best wishes
Michael

Bjarne, this sort of wood shaping is easy and a lot of fun. Just take it quietly and try to resist the temptation to take off too much in one hit. They tend to shape themselves and as suggested earlier, it's really hard to screw the whole thing up. Shaping blades and masts and oars are the fun jobs that make all the mucking about building the boat worth it

Richard

Originally Posted by Daddles

Shaping blades and masts and oars are the fun jobs that make all the mucking about building the boat worth it

Richard

??? !!!! Are they ?? !!!!
Must have missed it somewhere.
Might be because I'm a lousy woodworker, & lack characteristics like patience, tact,
co-ordination & eye for detail. So much so that the last foil I did was with an angle
grinder fitted with 40 grit paper. Took nearly 30 seconds per side & I resented every
single one of the last 58 of them. Passionately.

Soooooo... I hope understanding my predisposition to near-enough-is-good-enough,
high-lights my gob-smackedness about how easy MIK's templates made shaping
the rudder I just did for Teal. Easy, easy, easy !!
Only departure from plan was to make the bit that sits against the bench a bit wider,
and clamped my blank that far from the edge of my bench. The template sat on the
bench & by sliding it towards the foil, I could see where the foil needed to have
material removed. Marked said spots with pencil & planed them off.

Now, if only fairing hulls were that easy....

cheers
AJ

"I have been looking at something with 300g and i cant get a 5m2 sheet and polyester for a fair prize, so there will be enough for 2 or 3 layer on the bottom."

Bjarne, if you mean polyester resin to stick the cloth to the plywood, DON'T USE POLYESTER RESIN anywhere. It doesn't stick for long, but separates from the wood and water gets under it and the wood rots. I learned the hard way 30 years ago. Use epoxy, and the stuff I use is NM epoxy from http://www.nilsmalmgren.se/. It's great,and it's SWEDISH, so easy to buy. It cures hard in a longer time than WEST which is much too fast setting, but if it is getting to be cold weather, or you want it to harden fast, you can add an accelerator, which can be bought separately in a plastic bottle.

Nils Malmgren also sells glass cloth in 160gm/m2 which I think is fairly light. When you get to applying the glass to the bottom email me and I'll give you some tips about laying it out and filling it with the minimum amount of resin, which does not add strength, only weight. This kayak building site is one of many with PICTURES that show you how to apply glass cloth to plywood with the best technique and minimum amount of resin. http://www.oneoceankayaks.com/Shop.htm#plydex , Kayak builders know how to maximize strength and crush resistance with light weight. They go into rock gardens all the time. My kayaks have 2 layers of light cloth on the bottom for abrasion resistance.

Peter Lord, in Uppsala, Sweden