GF16 questions.

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matth6
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GF16 questions.

Post by matth6 »

Hello All.
I have been lurking this forum for about a year now and have finally decided to start a build of my own. This will be my first build and I have chosen the GF16 based on its simplicity to build, the fact that it will fit in my garage, and it fits my needs for now. I do have a couple of questions that I haven't seen answered elsewhere.

The local lumber yard with the absolute best prices on marine plywood for whatever reason does not carry 1/4". They have offered me 9MM instead, okoume marine AB. Per drawings the 1/4" is called out for the bottom and sides of the hull. Will this be too thick to bend or should I try and locate 1/4" or 6mm ply elsewhere? By my calculations this extra thickness of ply would add less than 30lbs to the overall build so i dont think weight would be a concern.

My second question is has anyone built this boat with Gunwales or on a similar boat? I would like to be able to mount a few pop-up cleats and stainless flush mount rod holders verses having the clamp on styles you see on similar aluminum boats. Should the Gunwale need to be Glassed to the hull or simply glued, epoxied, and painted?

My final question, and it might be a dumb one (first build of any kind here) is that it appears per the nesting drawings it might be possible to add a slight bit of height to the freeboard by simply cutting the side panels and transoms a touch taller, the rear transom would have to have a deeper radius or curve to maintain proper height for the motor i know. There seems to be some play there in unused plywood per nesting drawing. Coupling this with the added gunwales would this dramatically alter any performance or adversely affect anything? IN my mind I wont be altering the footprint, width or length, simply the "depth of freeboard" or are my assumptions off? The only reason I would do this is that I will have smaller kids in tow from time to time and it adds just a touch of extra safety.

Thanks for any input ya'll have. I can't wait to get started.

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VT_Jeff
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Re: GF16 questions.

Post by VT_Jeff »

matth6 wrote: Fri Mar 12, 2021 1:33 pm Will this be too thick to bend or should I try and locate 1/4" or 6mm ply elsewhere?
My .02: Definitely look elsewhere. Don't even consider it. And I'm the "You can probably make that work" guy on here. My advice based on my experience is this: trust and obey the designer.

Otherwise, welcome and good luck!
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Fuzz
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Re: GF16 questions.

Post by Fuzz »

Welcome and have a good time with your build.
About the plywood. I would call BBC and get them to give you a quote on shipping. If you can I would have them ship everything you need all at one time. I would plan on putting at least one layer of light glass over every thing so you will need extra resin and glass. I had them ship supplies to me in Alaska and it was very cost effective so I know the shipping to you will not be too bad.
At first glance I see no problem with the changes you want to make but I would see what the designer has to say.

piperdown
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Re: GF16 questions.

Post by piperdown »

Stick with finding 1/4". Every little bit of weight adds up and you'll use more epoxy than you suspect adding more weight. Even Menards carries 1/4 inch but through special ordering. I'd check first with Jeff or Reid as you get the best possible ply for the money.

I don't recall who, and they didn't get added to the build threads, but I did come across a GF16 with gunwales. They added braces between the seat frames to support the weight.

Adding a bit of height is not a problem, at least from a building point of view. I think others have done the same and I've got about 1 inch raised on mine (that's still a work in progress).
Eric (aka, piperdown)

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Re: GF16 questions.

Post by TomW1 »

There are several TX builders that got there plywood around there, maybe one of them will see your post and answer where you can find !/4". If not look for a TX builder on here and ask him. Almost everybody uses some 1/4" somewhere. Good luck.

Tom
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matth6
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Re: GF16 questions.

Post by matth6 »

Thanks everyone for your responses. I will definitely steer away from the 9mm ply. It turns out they have 5.2mm ply which is thinner than 1/4" for sure but the metric plans call for 6mm. The 5.2mm is only .032" smaller than the 6mm. Will this work in place of the 6mm? Again this is Okoume marine AB ply at 5.2mm in place of 6mm. By the time its all glassed top and bottom Id have to think this would be sufficient?

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Re: GF16 questions.

Post by piperdown »

matth6 wrote: Tue Mar 16, 2021 9:48 am Thanks everyone for your responses. I will definitely steer away from the 9mm ply. It turns out they have 5.2mm ply which is thinner than 1/4" for sure but the metric plans call for 6mm. The 5.2mm is only .032" smaller than the 6mm. Will this work in place of the 6mm? Again this is Okoume marine AB ply at 5.2mm in place of 6mm. By the time its all glassed top and bottom Id have to think this would be sufficient?
Pretty sure that's nominal, meaning they'd call that 6mm. JM can say for sure.

His lamination schedule, if you follow it to a T, is quite robust. I'm not sure if all his boats have this safety margin but I saw he put a 50% on the LB26, so I'd guess he uses a 50% safety margin in all his boats.
Most of us go a little more with the fiberglass. I haven't flipped yet and am still fairing the bottom but I went all the way to the rubrail with the 12oz biax fabric, that's after taping all the seams with 6" wide 12oz biax tape.
The critical points are keeping the frames where they need to be and the correct size. The hull relies on those frames for structural integrity.
Eric (aka, piperdown)

"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

piperdown
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Re: GF16 questions.

Post by piperdown »

The link has a pic to "semi" gunwales, more like inwales.

viewtopic.php?f=2&t=62456&start=10
Eric (aka, piperdown)

"Give an Irishman lager for a month and he's a dead man. An Irishman's stomach is lined with copper, and the beer corrodes it. But whiskey polishes the copper and is the saving of him." --> Mark Twain

matth6
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Re: GF16 questions.

Post by matth6 »

Thanks Piperdown for the info. I have another question for the collective brain. I may have free use of a 1998 30hp evinrude with remote steer short shaft 15", i do not know if it is a 2 or 4 stroke but the motor weighs about 115 lbs. The reason i am considering is that it may be free along with having only 30 hours of use so basically new. What reinforcements are needed to accommodate the extra HP on a GF16? IT seems that others have toyed with this much hp on this boat before but I dont know how it turned out. Also, being a short shaft and im not wanting to cut the transom down, has anyone had any experience with vance manufacturing drop down plates designed to use 15" shafts on 20" transoms? Any info is much appreciated.

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Re: GF16 questions.

Post by jacquesmm »

115 lbs on that transom will be fine. If you want, add a layer of tape all around the transom for safety.

Why use a bracket? Unless you plan to switch to a 20" shaft later, you can juts build the boat for a 15" shaft.
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