Fiberglass strips to use on male molds

Aloha, I'm building a 24ft outrigger canoe from plans and was wondering if anyone has used cured fiberglass strips in place of wood strips on a male mold? I'm not wanting to use wood for the hull as I know this boat will take a lot of abuse from my kids/ friends etc so I was hoping to do a solid fiberglass layup. The problem is I only have the plans for strip building with wood- has anyone used fiberglass strips instead? I (yes, I have no boatbuilding experience) figured I could glass some heavy cloth on a plastic sheet covered plywood, cut it into strips, staple the strips down to the stations, fair the gaps then lay CSM over that followed by 1208 double bias and then finish with CSM, pull it off the mold while leaving in some stations as permanent bulkheads and glass those in and then spend hours fairing the outer surface with fairing compound. So is this a dumb idea or is it possible? I think the layup schedule might be a little weak so I may have to use 4-6mm Divinylcell after the first layer of CSM....Not sure if this is possible but I thought I'd ask those in the know...

 

Hello Shinnosuke,

Can you post some more details re the design of your 24' outrigger canoe please?
Maybe a copy of the general arrangement drawing for a start?

Will your friends and kids be using it for surfing waves and inevitably coming into hard contact with the beach occasionally?
If you build the wood hull properly, and sheath it in glass and epoxy, then it is essentially a wood cored fibreglass hull, and it should be able to take a fair bit of abuse, and last a long time.

If you build the main hull with fibreglass strips, would you then also build the outrigger in the same fashion?
What do the plans specify for the cross beams connecting the hulls?

 

The plans are from the book " Building Outrigger Sailing Canoes" by Gary Dierking and it is called the Ulua. 18' long but the stations can be stretched 150% to 24'. My kids and friends will probably run into concrete piers, rocks, and anything else that will attract a thin hull haha... The hull is wood strips and the ama is foam with a center stringer of wood. The outrigger beams and float will be the same, I'm just trying to strengthen the hull. Here are some pics of the book and the canoe.

 

Here are a couple more screen shots:

 

Great book, cool boat, plan is not so good.

The beauty of wood is that it can be faired prior to laminating. The reason we don't see many boats stripped in glass is fairing the glass borders on nightmarish.

Someone will surely show us a picture of it being done, but wood is the magic. If you did not want to use wood; you could build formers from something like xps, then shape it, apply a solid frp skin, then remove it. But glass strips! Yikes. It might be a month of fairing and two months to stop itching.

Another thing and a misconception you have is boats are designed for impacts. When you make a boat so strong it won't take an impact and bounce back; it generally means breaks.

Another thing you failed to consider is a solid glass boat will sink like a rock. A wood sheathed boat; with the proper layup and a touch of added foam will float and can save the crew in a capsize.

Revise your plan.

I built some Dierking inspired amas. They are xps encased in glass. Works fine...not impact resistant at all. I digress.

 

Good points, the xps foam strip idea sounds doable with some fairing....
Yes, I did consider that a solid fiberglass boat will sink which is why it will have the front and back end encapsulated so it won't sink, much like the OC6 outrigger canoes here along with the OC1, OC2 etc that are all fiberglass construction...
And I know that boats aren't designed for impacts but having a stronger layup will mean less damage and I have seen an OC6 collide with a huge rock (the steersman, me, wasn't paying attention) and bounce off with a few scratches whereas a thinner shelled hull might've crumbled...
Mahalo for the info!

 

No. XPS has no shear and I only suggested it as a former. It would be removed after you have all the glasswork done, not a core!

It will all peel away when done with the glass, but not a good idea really versus a wood core. A wood core is also super easy to repair...it holds shape so well..

 

You don't use glass strips, you build a mold, male or female and use that to lay up the glass. The problem you are going to encounter are stiffness and weight.

That beeing said, to my knowledge the Ulua also exists in a foam sandwich version. The designer is helpful and active, contact him about your desired changes.

 

Yer, glass strips/ patches is a fine way to build a hull. A boat builder friend set up a temporary framework, spaced battens over frames, as you would set up for a double diagonal hull build, and then layed up flat glass strips/panels on a melamine table, stapled these to the battens, and then glassed the whole shooting match to build up the laminate thickness once the temporary frame work was covered.
Built a 60 foot displacement motor cruiser this way, with the staff keeping busy between jobs working on this project.

 

C-Flex is a proprietary method of building using "planks" of fiberglass rods.
C-Flex https://www.seemanncomposites.com/cflex/
https://www.seemanncomposites.com/__static/859a39bdeefe37e5fed9dcc87bc62144/cflex-manual-web.pdf
anyone with any experience using c-flex? https://www.boatdesign.net/threads/anyone-with-any-experience-using-c-flex.48137/

 

The beauty of Dierking's designs is they are light.

Before you endeavor to build the boat in solid glass; you really ought to consult with Dierking. Ten or fifteen guys can post on this thread~you can do its, but the boat will be much heavier for the same stiffness. The scantlings alone; heavier; the fairing of square sections; heavier. A wood craft gets pre-sanded round and gets lighter!

I would be willing to bet nearly double the weight for all glass. Unless you go to carbon/aramid, in which case; the all carbon boat is also not bombproof and cracks easier in impact.

 

Checks this Youtube series for some ideas on outrigger canoe building, by professionals