Thread: GIS material list

Howdy - just email me or PM me with your email address and I will send you the first part of the plan with the material list and basic description.

You can send me a PM (personal message) by clicking on the photo of me sailing my sailing canoe on the upper left of this message.

Please feel free to ask questions here.

Best wishes
Michael Storer

Thanks Mik for mailing me the first 20 pages of the GIS plans.

I was quite surprised not to find glass to sheet the entire outside hull in the material list.
OK, by using 6mm plywood it is not a question of strengthening the whole structure but more of giving better protection against impact by rocks etc.

Designers like M. Waters from smalltrimarandesign take a different road: He recommends sheeting the outside and the inside of the whole boat not only to stiffen or strengthen the plywood. The inside sheeting with a light class cloth also has the function to make sure the plywood is totally and long term protected against water.
I like that approach - what do you think?

And I have a question to the Dutch GIS fleet (is there 4 boats in the Netherlands?):
What were your boats approximate material costs (I guess it'd be pretty much about the same in Germany) ? What did you spend for the sailmaker?

Thanks and Cheers from Berlin,
GIG

Howdy,

This glassing is an increasing trend from some kayak and multihull designers. I think they don't understand the material and that it is not being based on any real data.

Derek Kelsall uses 6mm ply up to around the mid 20 foot mark (8m).with no glass being necessary - recommended for the bottoms of the hulls only. Woods designs also only use glass sheathing on the outside and glass taping or timber cleats on the inside.

My big advantage is that when I started in the wooden boat industry I spent 2 years working cutting out kits for boats from a lot of different designers. I know what everyone uses and chose the lightest and simplest materials out of my sample of experience.

Also we have the example of the 5m Jarcat in Australia.



Quite a big boat, carries a family of four and can use an outboard up to 25 hp.

It is built of 4mm ply with 75gsm glass on the outside only. Hundreds of these boats have been built. They are very reliable structures.

More glass adds weight without adding any functionality.

Adding glass on the INSIDE to stop water getting into the ply is a lot of work for little benefit. Dozens of high performance monohulls and catamarans in Australia find that three coats of epoxy (apply wet on wet as in the GIS appendices) works with complete success. So why complicate it more? Also glassing the inside of a hull is very messy and unpleasant.

Most kayak plans that talk about glass on the outside suggest 135gsm or 200gsm glass on the outside.

It makes the kayak designers that recommend 135gsm glass inside and out look like they are building both too heavy and too expensive.

I look at the jarcat and I think - does a little kayak need more glass than this?

As a designer and builder I have seen plywood kayaks of 4mm ply go from having 50mm glass tape on the seams only.

Then by about the mid '90s it had evolved to glass on the outside and tape on the inside.

Then in this decade there are a number of kayak plans that instruct builders to glass inside and out. It is just strange.

Fine for boat built specifically for going into rough, isolated places, but for the 95% of people that won't do that it is overkill.

The thing that the Jarcat shows us is that very thin and light glass can perform just as well as something much thicker and heavier, more expensive and more effort.

If you do have lots of rocks I would recommend using a 75gsm glass over the bottom and wrapping only 25mm around the chine to replace the function of the glass tape.

The other cool thing is this thin glass is a complete delight to wet out with epoxy.

Best wishes
Michael

Thanks Michael
for the detailed answer.
When it comes to boat building I just have a multihull builder background... glass everything.
So your thoughts are somehow new to me but sound very sensible.
Must read a bit more of the older threads, there's so much interesting information.

Cheers,
GIG

The Goat has been a huge success largely due to its sterling performance. That performance is a function of its very light weight (and MIK's design). That very light weight is largely due to all the bits MIK leaves out; add nothing that doesn't serve to improve performance and function.

As he states you would do well to add glass on the bottom IF your sailing area is full of obstacles that might scar or puncture the hull. Otherwise, 2" glass tape on the chines is all you need. BTW--I lobbied MIK for wider tape but followed his advice in the end. I used more screws than he calls for, however...10 in total instead of 6.

Haha

Where did you put the other four? I am sure you said, but I can't remember.

MIK

Two screws in each of the transom knees....which means I have to sit a little more forward...maybe a millimeter or two, right?

I would say so!