Anyone experienced with ply?

[stonedpirate]

Hello,

Went shopping about for marine ply today and found a good supplier of quality ply.

Since this is my first boat, i have no idea how think to make it.

My first plan was to use 3 skins of 3mm ply to make a 12" hull.

Then i thought about 2 6mm skins.

The 3mm felt bendy and easily snappable.

Does epoxy and fibreglass really harden these ply sheets right up?

It just feels like a flimsy building material.

Is 6mm ply too thick to bend into a nice curve without heating it?

Also, for the flat deck and transom, would 9mm be enough or 12mm?

Any advice on hull thickness for a bluewater hull and the way to go about it would be greatly appreciated.

Thanks

[tunnels]

Originally Posted by stonedpirate

Hello,

Went shopping about for marine ply today and found a good supplier of quality ply.

Since this is my first boat, i have no idea how think to make it.

My first plan was to use 3 skins of 3mm ply to make a 12" hull.

Then i thought about 2 6mm skins.

The 3mm felt bendy and easily snappable.

Does epoxy and fibreglass really harden these ply sheets right up?

It just feels like a flimsy building material.

Is 6mm ply too thick to bend into a nice curve without heating it?

Also, for the flat deck and transom, would 9mm be enough or 12mm?

Any advice on hull thickness for a bluewater hull and the way to go about it would be greatly appreciated.

Thanks

Have you thought about getting some plans along with all the instructions on what to make the boat out of and how to make it ??? you do know the sharp end is the front !!

[stonedpirate]

lol

I have to design it myself because no boat exists.

No naval architect would risk liability designing it for me.

I'll just buy some test ply and epoxy and mess about with it, kick it, throw bricks at it ect. I'll figure it out on my own. Just costs more.

[tunnels]

Ok
Need to do some reading and sketching ideas on paper to get some sort of an idea at what you are going to undertake and gain a little understanding on what to use and where and how . Enthusiasium is a dangerous thing and the killer of dreams and the dream"s

[Grant Nelson]

Check these out...

http://www.boatbuilder.org/index.htm
http://www.origamimagic.com/

[ancient kayaker]

Dear Stoned:

It's almost certain that the boat you need already exists as a plan, kit or ready-made, unless you want something unique. Designing your own boat is a bit like designing your own car or airplane. Been there, done that, had a ball actually but it took a while and for me the point was for to learn. If you just want the boat get professional help. Er, no not a shrink, a designer

-Abby


Now about ply: a single layer of 3 or 4 mm ply is about right for a canoe or kayak, for a 12' sailboat 6 or 9 mm would be suitable, 12 mm perhaps for the bottom if intended for serious heavy duty and abuse. Transoms are generally thicker than planks and bottoms. Plywood flops all over the place until bent around a curve and glued to another curved piece, then it stiffens up to an amazing degree.

There's all sorts of ways to put the ply together to make a boat. Some are easier than others. I suggest you read a few books, buy a few study plans, and lurk around the forum for a while before you spend cash on materials.

[pistnbroke]

to show you the whole build process why not go to www.epoxy-resins.co.uk ...scrolldown to a boat called morgan and click on the photo ..you will get loads of photos of how it was built.

[stonedpirate]

Cheers guys.

I'll check morgan out.

I am still waiting for my books to arrive next week.

I ordered "Gougeon Brothers on Boat Construction" and "Devlin's Boatbuilding: How to Build Any Boat the Stitch-and-Glue Way".

Hopefully that will give me enough insight for the construction

The reason i asked early was so i could figure out the rough cost of the boat in total.

Looking at about $10k fully rigged.

[jwboatdesigns]

Originally Posted by stonedpirate

lol

I have to design it myself because no boat exists.

No naval architect would risk liability designing it for me.

I'll just buy some test ply and epoxy and mess about with it, kick it, throw bricks at it ect. I'll figure it out on my own. Just costs more.

Paul Fisher of Selway Fisher design has in fact drawn up a boat thats about as suitable as any that I, or anyone else ( including people posing as award winning designers) is likely to produce.

http://www.selway-fisher.com/PCup16.htm#CRO

He does a smaller version called Micro 8, I'd suggest that paying the very modest fee to the designer for plans for the 10 ft version would answer pretty much all your questions and get you under way with your build .

John Welsford. Award winning designer.

[stonedpirate]

Thanks John.

I have seriously considered the micro 10 and was curious about Gimli.

Just was a bit uncomfortable with the delta rig. Heard some bad reviews about it. Also, the swing keel makes me feel uneasy. I can envision it snapping off in the sea

I asked him some questions about it a while back but got a short response. I get the feeling he doesnt like these boats or the nutters that want them He also mentioned that it cant sail upwind.

I wasnt saying you were a poser. I know you and Paul are quality and have spent much time on both your sites.

Whatever happened to gimli?

Plus i love fafnir.

[jwboatdesigns]

Originally Posted by stonedpirate

Thanks John.

I have seriously considered the micro 10 and was curious about Gimli.

Just was a bit uncomfortable with the delta rig. Heard some bad reviews about it. Also, the swing keel makes me feel uneasy. I can envision it snapping off in the sea

I asked him some questions about it a while back but got a short response. I get the feeling he doesnt like these boats or the nutters that want them He also mentioned that it cant sail upwind.

I wasnt saying you were a poser. I know you and Paul are quality and have spent much time on both your sites.

Whatever happened to gimli?

Plus i love fafnir.

Gimli would take about $5,500 00 worth of time to produce full plans for, that would include all the calculations and figures needed to get her past the bureaucracy. I'd need at least 5 sets of plans with deposits paid before I'd consider carrying on with the proposal. Note, that proposal was drawn to show the Around in 10 people what would be required to do well in that event, race or cruise. Gimli would cost about fifty grand to build, the keel for example being post tensioned carbon fibre on a tapered carbon tube pivot in UHMW bearings, the hull being carbon over a mix of divinycell closed cell foam and Nomex honeycomb, and the rig being carbon spars with kevlar sails.
The design is a racer, and designed to win.

I note by the way that the Around in 10 event has disappeared, and the site, if it has not already gone, will be soon

Fafnir though would cost about 10% of the above, and be a much nicer boat to sail, will carry a great deal more equipment, will sail more easily, ( not necessarily faster although in some conditions that could be the case) and can be built in a garage or under a tarp shelter by a first timer.

And sorry, although I appreciate your compliments, no I wont be designing a 10 or 11 ft version.

I note your comment about Pauls Micro boats, and that they wont sail to windward. Thats about what I'd expect, a heavily loaded boat only 10 ft long in any sort of seas will be unlikely to make progress to windward. If Paul Fisher cant do any better than that with a plywood boat, and I needed to design a fifty grand carbon fibre racer to do it, then its worth your while thinking over why that might be.

That said, Captain Cooks Endeavour could only sail to windward if the tide was going in the right direction or if the wind and sea was perfect, and even then not well. As you'll no doubt know, he made it from England down to our parts, up to Tahiti, and back to England.

You'd need to study the old sailing ship routes and the seasonal wind patterns very carefully.


John Welsford

[stonedpirate]

Cheers John.

I'll just accept that serge is a freak of nature.

No real design skills, whipped up a boat by trial and error and sailed around the world on it and did quite well to windward.

Plus his sails look tiny.

[jwboatdesigns]

Originally Posted by stonedpirate

Cheers John.

I'll just accept that serge is a freak of nature.

No real design skills, whipped up a boat by trial and error and sailed around the world on it and did quite well to windward.

Plus his sails look tiny.

No real design skills is not quite right, whipped up by trial and error is also not an accurate description of the facts, and "did quite well to windward' is also something of an exaggeration.

Serge is a member of the Micro Cruising yahoo forum and occasionally posts there, he demonstrates good knowledge of the design of small cruisers, his book and his postings show that he carefully researched the issues, his build shows that he had a good appreciation of what was needed and the skills to satisfactorily complete the project.
Of course the sails are small, a boat of this size will not have the stability to carry much sail area, and yes it would sail to windward, but only in relatively calm conditions and moderate winds. Those small sails being one reason, a small boat will only have limited sail carrying ability, the windage and resistance of a small boat in open waters will require more drive than can be generated by the limited stability and sail area.
What designers such as Paul Fisher and I would consider reasonable performance to windward in a boat designed for the open sea, is a great deal better than any of these small, heavily laden boats will achieve.

You could if you wished, join that forum and see if he was interested enough to answer your questions. I am sure that you would find his answers useful.

John Welsford

[stonedpirate]

Thanks again John. Huge help.

I will join. I sent him an email a few months back but he ever replied.

Hopefuly i'll have more luck on the forum.

Cheers

[Nissane]

I hope I'm not hijacking this thread, but I have a similar question but different .
I'm building an off road slide on camper (caravan) for my 4wd so I can also tow my boat behind. I was advised by 2 different boat builders.
One said to use 7mm CD Ply and to fiberglass the whole thing inside and out.
The other said to use 9mm and to treat it with Evendure then paint it. But if I think it's not strong enough, to fiberglass it.
I'm trying to keep the weight down so I would prefer to use 7mm. Do you think it's going to be strong enough or should I use the heavier stuff?