GF12X-LS (Low Sheer)

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Arm&Hammer
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GF12X-LS (Low Sheer)

Post by Arm&Hammer »

If you have been following Cracker Larry's latest GF12 thread, you have seen my posts about my GF12 build plans. I picked his brain quite a bit, and CL, I thank you again for your valuable input. My camera is fixed and I have started building, so it was time to start my own thread. To summarize, I wanted a small planing boat that I could load in a truck bed by myself, but was stable enough for two people to stand in and fish. I also have a target cost of $599 before hardware and paint (not including tools, supplies, etc.). Like most builds, achieving this cost goal will depend on "epoxy management". I purchased the GF12 kit, so I only have 3 gallons.

Modifications:
-I decreased the beam of the boat by 3" (fairly easy with a GF).
-I lowered the sheer by approx. 2-1/4" to align with the lowered transom (for 15" shaft outboard).
-I lowered the mid and rear seats by approx. 1-1/8", and the front deck by approx. 4-1/2" (2-1/4" below the now lowered sheer).

I also substitued 3/8" for 1/2" ply, but will strengthen some areas to make up for it.

After making these changes, I was able to change the nesting to 3 sheets of 1/4", and 2 sheets of 3/8", including rubrails. I will also be using the scrap ply to make cleats. Below is a shot of the nesting.

For the 1/4" ply:
Image
Note the extra 1/4" clamping board.

For the 3/8" ply:
Image
Note the extra bow transom.

In CL's build, he mentioned the flat that was created due to the long side butt blocks. To minimize this, I removed some of the butt block, leaving just enough of the upper side for attaching a cleat:

Image

For the stern transom, because I am only using 3/8" ply, I added an extra 1/4" clamping board. I also put one layer of tape below the clamping boards where the transom is only 3/8" thick so that it will have glass on both sides. I'm not sure if it was necessary, but I wanted to compensate since I am not using 1/2".

Image

I made the bow transom out of 2 layers of 3/8" since it will probably see a trolling motor from time to time. I'm not sure if this was necessary either, but it "felt right" to have the extra strength their. It definitely helped when putting in the temporary screws. Speaking of that, it wasn't very difficult to bend the sides to meet the bow transom. Maybe this was due to the lowered sheer. And once attached, the angle is significant enough that I didn't have to open it back up. I brushed in the epoxy, filled with epoxy glue, and then taped wet on wet like CL did.

I will not have enough epoxy to glass the inside bottom of the boat, so I used the butt block per the plans (instead of a FG splice, which would be my first choice if I had extra epoxy/glass). It bothered me at first, having a butt block in the middle of the floor, but now that it is in place, it is not quite the distraction that I thought it would be. (It is only 1/4" ply, tapered nicely on each end, which is small compared to the ribs in the bottom of most aluminum boats that I fish from.)

Attached are two pics of the rough assembled hull. No cleats yet - the seats are sitting loosely in place.

Image

Image

Since these pics, I have all of my cleats cut. I hope to glue them in place and install the rubrail soon...



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Cracker Larry
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Re: GF12X-LS (Low Sheer)

Post by Cracker Larry »

All right AH, looks like you're off to a great start 8) Glad to see your thread up.
Completed GF12 X 2, GF16, OD18, FS18, GF5, GF18, CL6
"Ships are the nearest things to dreams that hands have ever made." -Robert N. Rose

jbo_c
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Re: GF12X-LS (Low Sheer)

Post by jbo_c »

Nice work. I like the idea. That boat's gonna be tight, though.

Jbo

Arm&Hammer
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Re: GF12X-LS (Low Sheer)

Post by Arm&Hammer »

jbo_c wrote:Nice work. I like the idea. That boat's gonna be tight, though.

Jbo
Thanks. Curious what you mean by tight though. For two people standing up and fishing, maybe, but I wouldn't guess any tighter than other 12' boats. It has the same floor space as the GF12, less 3" of beam, and the GF12 is pretty roomy for a 12' boat.

If you mean tight on the epoxy, don't I know it! To be fair, I have to admit that I had a little left over from my CC14 build which got me up to this point. But there is a lot of glass to wet out and surface area to cover, so I have my work cut out for me.

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Re: GF12X-LS (Low Sheer)

Post by jbo_c »

I meant tight with two people fishing it. - though probably tight on epoxy too.

Jbo

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Cracker Larry
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Re: GF12X-LS (Low Sheer)

Post by Cracker Larry »

Matt used to put 3 people in his, and go spearfishing, offshore :wink: It bigger than it looks in the picture.
Completed GF12 X 2, GF16, OD18, FS18, GF5, GF18, CL6
"Ships are the nearest things to dreams that hands have ever made." -Robert N. Rose

Arm&Hammer
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Re: GF12X-LS (Low Sheer)

Post by Arm&Hammer »

No plans for offshore, especially with the lowered sheer (and considering the skipper :oops: ). But if I lived in FL, I would fish the Mosquito Lagoon in this boat all day.

I got the cleats glued in tonight. Kind of a pain using 2 ply of 3/8". It cost me a little extra epoxy, but the 2xply should give me a little more strength since I'm going to have cutouts in the frames, and it saved me a little money in buying add'l wood.

I'm going to spend some quality family time this holiday weekend. Next week, I hope to get the rubrail on and get it flipped.

Have a great Labor Day weekend.

Arm&Hammer
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Re: GF12X-LS (Low Sheer)

Post by Arm&Hammer »

The rubrails are on, with one of the three layers on the inside. For the front of the boat, this inside rail extends from the ears on the front mid-seat frame to the bow transom (above the lowered front seat). For the rear of the boat, the inside rail extends from the ears on the rear mid-seat frame and ends at the rear seat frame, although it looks like it extends to the stern.

To explain, the ears on the rear seat frame only stuck 2" above the rear seat, so I eliminated them (other than a short tab for alignment purposes). To add back in some stiffness, I put a piece of 1/4" ply on each side of the rear seat, approx. 3-1/2" deep. This appears to be a continuation of the rubrail, but extends below the rear seat with enough surface to mount a cleat. I will post some pics soon.

The other thing I like about putting one layer on the interior is that it matches the thickness of the butt blocks when looking from above.

Today I flipped the boat and started stitching the bottom from the stern forward. Once I got past the mid-seat, I checked my progress to see if I had a rocker or hook. Unfortunately, there was a significant rocker of 1/4" plus. I did some searches, and learned that some others had experienced the same problem. I posted a question on Cracker Larry's GF-12 thread. As typical, it was excellent and thorough advice (please check his thread for details).

The only problem I had was with the solution. He used his existing jig to pull everything into alignment. I am not using a jig on this boat (not required per the instructions), so I had to come up with something else.

After removing the stitches, I grabbed two straight pieces of Ipe' each 5' long, that I had from an old deck project. I screwed one along each side of the rear portion of the bottom to hold it straight. With this section of the bottom now straight (no rocker), the bottom interfered with the rear seat frame. I removed this frame, and the bottom of the boat now lays nice and straight from the rear mid-seat frame to the transom, nearly 5'.

This also pulls the bottom of the boat up between the side panels approx. 1/4" at the mid point. For reference, the bottom exterior is even with the bottom of the side panels at approx. the splice location. It will take some extra work to do this seam properly, but having the planing surface flat should be worth the effort.

Arm&Hammer
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Re: GF12X-LS (Low Sheer)

Post by Arm&Hammer »

To clarify my previous post, to ensure that the bottom of my hull was flat from the stern to the rear mid-seat frame, I used braces:
Image

Using the bottom of the stern transom and my rear mid-seat frame as fixed points, the bottom "pulled up" between the side frames at the mid point:
Image

Hopefully the pictures explain it better than my description. I am happy with the result - the first 5' of the bottom of the hull is flat.

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Cracker Larry
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Re: GF12X-LS (Low Sheer)

Post by Cracker Larry »

My eyes ain't that good :help:

Image

Perfect 8)
Completed GF12 X 2, GF16, OD18, FS18, GF5, GF18, CL6
"Ships are the nearest things to dreams that hands have ever made." -Robert N. Rose

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