GV 11 materials question

Boats up to 15' for oars, power or sail. Please include the boat type in your question.
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Re: GV 11 materials question

Post by Jeff » Mon May 11, 2020 8:29 am

jnb, call me!! The 4 inch 9 ounce tape has been replace with 4 inch 6 ounce woven as the 9 ounce is no longer available. Call us at 772.742.8535. Jeff



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Evan_Gatehouse
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Re: GV 11 materials question

Post by Evan_Gatehouse » Mon May 11, 2020 2:43 pm

For the GV11, I'd use 12 oz biaxial tape. Much stronger, and quantity required is not that much.

For smaller, non planing boats, 4" x 6 oz woven is OK.
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

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Re: GV 11 materials question

Post by jnb » Tue May 12, 2020 12:59 pm

Great, thanks guys. Just about to pull the trigger and order materials.

Evan, should the transom get any fiberglass as well? Or is it strong enough as is with the knees and supports?

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Re: GV 11 materials question

Post by jnb » Tue May 12, 2020 1:53 pm

And one final question, should the interior of the hull be glassed before the frames are attached (so there would be longer sheets across the whole hull) or after (which would involve different pieces navigating around the frames)?

Seems like glassing before the frames would be easier, but I'm not sure if there is some other downside.

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Re: GV 11 materials question

Post by Reid » Tue May 12, 2020 3:57 pm

jnb wrote:
Tue May 12, 2020 1:53 pm
And one final question, should the interior of the hull be glassed before the frames are attached (so there would be longer sheets across the whole hull) or after (which would involve different pieces navigating around the frames)?

Seems like glassing before the frames would be easier, but I'm not sure if there is some other downside.
You are correct. Definitely glass the inside of the hull prior to installing the frames.
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Re: GV 11 materials question

Post by OneWayTraffic » Tue May 12, 2020 5:05 pm

I don't have the plans for that boat but if an order is stated in them then follow that unless you like going it alone and taking the consequences for screwing up. Sometimes there is more than one way to do things and the designer picks what he thinks is easier, and sometimes there is really only one correct way to do it. It's not always obvious which is which.

In my D5 I taped each compartment as stated in the plans, then went around with 6oz glass for protection later on. This was a lot of work, but I was new to glassing, and could do every section one at a time, then sit back and absorb the lessons before starting the next one. That worked for me. I needed to leave the frames in so the hull didn't lose shape. It was not built on a jig. Doing the outside was much easier and faster, without the frames in the way.

Larger boats built on a jig, the usual way is to tape the outside, then glass it, then flip on to a cradle removing frames and stringers and glass the inside. You need to be really careful that the hull does not lose shape. Some designs and designers even of large planing boats specify that the frames be left in and taped around while in place. I suppose that this helps the hull keep shape, but there will be a lot of fiddling around with the inside glass.

So what do the plans say? If you build the boat the stitch and glue way, without a jig, then tape the frames in place with no inside glass specified then you may have no choice but to leave a frame or two in, or glass the outside first on a simple jig then make a cradle. If the inside is specified tape only, it won't really matter so do as you please.

Other bits of advice I can give:
Always make sure that you have got a nice smooth radius on ALL corners of at least 12mm (1/2").
Get a bubble buster roller and keep it clean in acetone (I had to strip 5 linear metres of 2 layers of 400g biaxial off my C17 thanks to air bubbles!)
Never do more in one day than you can check and keep an eye on. If it's not working out it's a lot easier to rip it off before it cures. In my second attempt at glassing the hull, I did each side over several days when temps were right (glassing in a greenhouse) and accepted that I would have a lot of overlaps and extra work. I still needed to spend hours on the bubble buster and heat gun.
Anything can be fixed. If you have a look at my posts there are some tremendous cock ups. :D

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Re: GV 11 materials question

Post by Evan_Gatehouse » Tue May 12, 2020 5:40 pm

You've got to glass the interior AFTER the frames - the frames define the shape of the hull so they have to be there first or there is no boat shape!

It's not a big deal and you can more efficiently use the pieces of glass in smaller pieces. Use cheap plastic drop cloth material as a template in the bow area to help cut the correct shape of glass (rather than trimming the glass several times to make it fit)

No glass needed on transom. The knees and corner brackets and clamping board provides ample strength

I don't use a roller. Just a 4" auto body squeegee. With a single layer of glass its not hard to get all the bubbles out and move the resin around. It's also easier to clean
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

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Re: GV 11 materials question

Post by OneWayTraffic » Tue May 12, 2020 6:48 pm

Evan_Gatehouse wrote:
Tue May 12, 2020 5:40 pm
You've got to glass the interior AFTER the frames - the frames define the shape of the hull so they have to be there first or there is no boat shape!

It's not a big deal and you can more efficiently use the pieces of glass in smaller pieces. Use cheap plastic drop cloth material as a template in the bow area to help cut the correct shape of glass (rather than trimming the glass several times to make it fit)
That's the final word then. :)
As a designer Evan, is the strength difference between glassing before and after a big deal, or is it mainly about the construction procedure and convenience? If you built the GV11 on a jig, which would be more work, glassing the outside like say the FS then flipping on a cradle would it really matter?

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Re: GV 11 materials question

Post by Netpackrat » Tue May 12, 2020 8:56 pm

I think if you wanted to glass the interior before installing frames, the way to do that would be to assemble the boat in a basket mold.

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Re: GV 11 materials question

Post by Evan_Gatehouse » Wed May 13, 2020 7:59 pm

It's not that big a deal to glass after the frames are installed. You can glass the bottom before the transom knees are installed so it's only really 3 panels.

Certainly it's a LOT less work than creating basket molds or exterior framing.

No, there is no strength difference. The hull is locally stronger right at the frames, where they are taped to the hull. So having a start/stop at a frame doesn't affect anything
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

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