GF12X-LS (Low Sheer)

[Murry]

That looks great A&H

Fantastic work!

Daniel

[Arm&Hammer]

I've got the bottom tacked on. I had to flip it and clean up shop for family plans this weekend.

General view:


Another general view:


A shot looking down at the side butt block, showing the inner rubrail. The reduction that I made in the size of the butt block helped alleviate, but not eliminate, the "flat" from the side.


A shot looking at the stern. I trimmed the sides of the butt block where the tape will go. It should allow for water to drain a little easier down each side, and I like the way it looks. Also note the rear frame. I had to trim it down to 2-1/8" on the bottom in order to fit my gas tank under the rear seat. That is shorter than spec, so I doubled up the 3/8" ply there. It is now 3/4", and with the stiffness that the buttblock adds to the bottom, I don't think I will have any issues.


A shot of the front rubrail. Note that I still haven't cut an opening in the front frame. I am at a decision point. On a larger boat for larger waters, I would go the foam route. On this boat, I am considering sealing the front compartment, and putting an 8" diameter deck plate on the frame face. The advantage is that it will give me some buoyancy, and dry storage if necessary. The disadvantage is that I lose the ability to store heavier objects (anchor, batttery, etc.) up front to balance out the boat, but there isn't a lot of usable space there since I have lowered the deck significantly. Thoughts?


The next step is to start taping the inside. The boat is square within 1/16", and is very stiff with the bottom now attached. I like CL's method for taping the inside chines: removing the seat frames and doing the chines with one length of tape on each side. Barring any unforseen issues, I will be doing it that way, hopefully soon...

[Arm&Hammer]

I debated a drain plug due to the size of the boat, but took the sage advice of others and will put one in (currently overdrilled to 1-1/2" and filled). Better to have it and not need it than....

I glassed one side of my frames, flipped it, and glassed the bottom last night (a challenge doing it myself wet on wet, but the low temp helped out). I will glass the other side of the frames tomorrow, and that should be it for "required" glass.

I may glass the inside exposed floor, but that will depend on how much epoxy I have left. Currently, I have just under 1/2 of my 3 gal kit remaining. I am pretty satisfied with the amount used so far (bottom tape and cloth put a big dent in it), but there is still a lot to do (I imagine the fairing will consume quite a bit.)

A question for other GF builders: What was your final transom height? because this boat is low sheer intended for smaller waters, I cut the transom down from 20.5 to 15.5", giving me a vertical transom height of just over 15". I thought this would be just right for a "typical" short shaft engine. I happen to have my brother's old '83 Johnson 4.5, so I put it on my boat for a quick check. Turns out it has a 17" shaft length (measured vertically from transom to top of cavitation plate). This puts the cavitation plate about 2" below the bottom of my hull. He still has the original owner's manual, and it specifies this motor for a 15" transom. Not satisfied with that, I did a search of several current motors (yamaha, tohatsu, mercury, etc.). It turns out that most of their "short shafts" vary in vertical transom height from mid-16" to low-17", atleast in the 8-15hp range.

From what I have read here, the optimal height of the cavitation plate is even with the bottom of the hull (or just slightly below for a GF. My question is, should I build up the transom now, or see how it performs first? I don't have a new motor yet, but I hope to get something in the 8-10hp range in the spring. I appreciate any tips.

[TomW]

The best performance for a motor with a planing hull is for the cavitation plate to be even with the keel or slightly higher. This still keeps the prop below the keel but reduces the drag from the motor's shaft. So if I were you I would wait till you have you motor and then raise the transom the appropriate amount, who knows you may get a newer motor where 15" is 15". It will be easiest to do this if you have not attached the clamping board yet.

Tom

[Cracker Larry]

I'd wait too. This isn't a speedboat and an inch won't make a lot of difference. She looks really good! I think it has better proportions skinny than it does fat.

It will be easiest to do this if you have not attached the clamping board yet.

I'm pretty sure the clamping board is already attached.

[Arm&Hammer]

who knows you may get a newer motor where 15" is 15". Tom

Thanks for the input Tom. Looking at the specs on new outboards, I can't find one that is truly 15".

Almost all manufacturers have their specs online, or a downloadable user's manual. For example, the new Tohatsu 8/9.8 four stroke has a transom height dimension of 17.1". Same thing with Yamaha in the same HP range. If you could point me to one with a true 15" transom height, I would appreciate it.

[Arm&Hammer]

I'd wait too. This isn't a speedboat and an inch won't make a lot of difference. She looks really good! I think it has better proportions skinny than it does fat.

Good point - I'll wait. If necessary, building up the transom height won't be all that difficult in the spring. I'm just embarassed by the newbie mistake. I had all of the information that I needed for free online, and I should have doublechecked before cutting. Possibly this is per Jacques plan - it is safer to keep the engine a little lower. (As designed for a 20" shaft, the cavitation plate would still be 1-2" below the bottom of the hull per the outboard specs I checked).

Thanks for the compliments! She is coming together nicely, better than I though w/o a jig. I need to get some new pics up soon. The proportions feel about right, but even 3" narrower, she still seems a LOT bigger than most 12' jon boats!

[shine]

The advantage is that it will give me some buoyancy, and dry storage if necessary. The disadvantage is that I lose the ability to store heavier objects (anchor, batttery, etc.) up front to balance out the boat, but there isn't a lot of usable space there since I have lowered the deck significantly. Thoughts?.

You can have both if you subdivide the compartment

[Arm&Hammer]

Thanks to everyone for their input.

My brother called yesterday, asking for some updated photos.

Here is a shot of the bottom. Since I narrowed the beam, I was able to do the bottom with one width of cloth (the roll I received was a couple inches wider than specified). This allowed me to wrap to the top of the bow and stern transoms.


Here is a shot of the inside. Everything has atleast one coat of epoxy, except for the seat tops, which won't be glued on until after I paint the inside of the frames. I put the resin on the front deck for reference. That is what I have left from the 3 gallon kit.


I hope to get the runners glued on and glassed soon, but cold weather is coming, and I might not get much further until spring.

[Arm&Hammer]

Snow is in the forecast for next week, so I had to get to a stopping point.

-I got the runners on. I glassed them, but ended up with a lot of air pockets on top of the runners , so I ground it off of the top. Instead of re-glassing, I put a 1/4" thick piece of Ipe on top of each. It is extremely hard and durable wood (not a joy to sand), but it should give me a very tough material should I ever hit something that scratches through the graphite and primer.



-I have the bottom/sides decently faired to the point that I could not see the little pinholes/divots/etc. I put on two coats of S3 primer last night. This will give the bottom UV protection until the spring. At that time, I will sand it down, finish fair, prime, and graphite bottom/paint sides. I will post some pics after vacation. Putting primer on really makes it start to look like a boat!



Off to Merritt Island, FL tomorrow for Thanksgiving, and some fishing in one of my favorite spots in the world - the Indian River Lagoon.