Monroe Malahini

Designs for inboard or outboard power

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obd
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Re: Monroe Mahalini

Postby obd » Mon Oct 17, 2016 7:02 pm

If building up your sheers and/or chines in laminations, scarf joints not necessary and butt joints adequate as adjacent laminations serve as butt blocks. I am doing my chines in triple laminations. The individual laminations are very easy to handle and bend effortlessly with no steam or boiling water required. Glen-L's book is pretty emphatic about the importance of using quarter-sawn lumber. "Quarter sawed lumber results in ideal vertical or edge grained boards, while plain sawed lumber provides boards of flat grain which are not as desirable for most uses in boatbuilding."

PeterG
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Re: Monroe Mahalini

Postby PeterG » Tue Oct 18, 2016 7:55 am

To add a little to OBD's comments above, scarf joints in the individual laminations are not really necessary, especially if you are working with three or more laminations and using epoxy adhesive. However the butt joints in each lamination should be staggered away from each other to prevent weak spot if the butt joints are too close.... for instance if you need 15 feet of chine and you have 8 foot pieces, you could make one lamination from an 8 foot piece plus a 7 foot piece with a butt joint, but the next lamination should be something different, like an 8 foot piece with 3.5 foot pieces on either end, then the next lamination put the butt joints between the previous ones.
Personally, if going with two laminations, I would use scarf joints. They will bend and form a smooth fair line more easily.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Thompson
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Location: Monroe, Ga

Re: Monroe Mahalini

Postby Thompson » Mon Oct 31, 2016 7:55 pm

I have a transom question. I hope I haven't screwed up. I made transom frame pieces and transom plywood by the patterns. I cut 13 deg. angle on the bottom of the frame piece then layed it on the 3/4 plywood to determine where it needed to be cut, the same angle. Then I glue it altogether. I've done nothing to the sides and top. Figuring that would come with faring. Studing the plans for something else I saw a note "All transom dimensions are given to the outside back surface of the 3/4 plywood". That means the plywood would need to be bigger, and there is Note about that. But also the frame pieces would be some dimension bigger also. If the frames pieces also have to bigger, why have a pattern. I had a question in my mind about this, but some how reasoned it away. Figured I'd better get this right before start putting this on the building form and had a problem getting things to line up. I guess i could glue, epoxy, a piece to the bottom and shim the notches. Any help clearing this up would be greatly appreciated. Thanks.

Thompson
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Re: Monroe Mahalini

Postby Thompson » Tue Nov 01, 2016 4:42 am

More transom questions. When your talking the thickness of the transom where the motor attaches. I assume that's at the motorboard, not the whole transom. My plan is. I used 3/4 DF marine ply for my transom. I was going laminate a piece of 1/4 mahogany to the outside when i did the planking for the sides and bottom, or after the flip. For motorboard I was going to use an additional 3/4 and 1/2, making it a total of 2 1/4". Opinions??? Thanks
Lyman

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hoodman
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Re: Monroe Mahalini

Postby hoodman » Tue Nov 01, 2016 6:55 am

If you mess up with the transom angle and need to add some material then there is no issue with adding strips of wood and re-fairing. I had to do that in several places in the aft of my boat. Along the transom and along the chines. It's something you can deal with and not a show stopper.

Yes the thickness is at the motorboard. If you have the thickness of the transom 3/4" plus a 3/4" motor board plus 1/4" veneer that's a total thickness of 1 3/4". If you ad an additional 3/4" in thickness to your motorboard that would get you to 2 1/2". Is that what you were thinking? Your motorwell sides will then tie the motorboard area of the transom into the battens and the rest of the boat. Here's some helpful information from Glen-l with regards to motorwell construction:
http://www.glen-l.com/designs/outboard/motorwell.html

PeterG
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Re: Monroe Mahalini

Postby PeterG » Tue Nov 01, 2016 7:07 am

You are correct, the pattern is for the aft face of the transom. Extra material has to be added to the bottom edge and the sides so the edge can be beveled for fairing. The bevel on the bottom edge needs to be 13 degrees (12 degrees transom tilt plus 1 degree downward slope of the keel). Basically your transom is about 3/8" undersized along the bottom and the sides. I hesitate to recommend this, but you may want to consider replacing your transom, start over with new plywood and frame pieces. Adding material to the edges would fix the one you made, but the plywood and battens and keel attachment will be dependent on the glue joint at the added material instead of the grain of the frame.
When I made my Malahini transom, I drew it out directly on the aft face of the plywood ( I didn't use the patterns) and carefully transferred the centerline and reference lines onto the forward/inside face. I then laid out and cut the frame pieces per plan but added 3/8" extra material to the outer edges (you can add more extra, it just needs to be at least 3/8"). I then attached (screwed, not glued) the frame pieces to the inside face of the plywood, laid it down with the aft face up and cut the bottom edge and sides with a saw set to 13 degrees for the bevel. Cut the top edge square, it will not need any extra material because of the transom tilt and the angle that the deck meets it. One thing I tried before cutting the transom, use a utility knife and precut through the face layer of plywood along the layout line. This will keep the saw from splintering the face layer as you cut and gives a nice clean corner/edge to fair to.
After I cut the transom out, I prepped the edges back by planing and sanding to the layout line and made sure the edges still had the 13 degree bevel. I then removed the frame pieces to make the notches for the battens, keel, chines and shears. I assigned a thickness of 13/16 inches for the battens and 1-1/4" total thickness for the keel (3/8" ply plus 7/8" lumber). These notches will be angled at 13 degrees like the edge of the frame.
A suggestion: Have you decided whether you are using a long shaft (20" transom height) or short shaft (15" transom height) engine for your boat? The plans are dimensioned for a short shaft but if you are building for long shaft, the cutout will need to be higher up the transom, the horizontal 2 x 4 stiffener will need to be moved up and the transom knee extended to meet the 2 x 4.
One more piece of info, the drawing and pattern for the transom knee don't agree. The drawing has 12 inches along the keel, the pattern has 13 inches. Make it 13 inches like the pattern, you can't go wrong.
Your plan for the final thickness of your transom will work just fine.
Post pictures of your progress!
Last edited by PeterG on Tue Nov 01, 2016 2:44 pm, edited 2 times in total.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Thompson
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Location: Monroe, Ga

Re: Monroe Mahalini

Postby Thompson » Tue Nov 01, 2016 9:49 am

Thanks Matt and Peter. I guess it's decision time. This is the first time I've worked with epoxy. That stuff seams rock solid and anything you glue together with it ain't coming apart. At the same time the transom seams like a pretty important part. I was already thinking of adding a gusset where the chine, sheer, battens tie to the transom. If i go with fixing what i have that might help.

Bevel sides at 13 deg. also. Put 13 deg on the bottom was not to difficult, it straight. I used a jig on my tablesaw and circular saw. But the sides. That means jig saw or bandsaw. Don't know how comfortable i am with that. I beveled notches in the frame bottom. Do you bevel the notches in the side pieces at this time as well? It would be easier before it's assembled.

I made my knee from pattern 13" and I'm planing on a 20" transom ht.

I have to get another sheet of 3/4 to beef up motorboard, maybe I'll make new transom. Hate backing up.

I'll try to include saw photos if i can figure out how to do that. I'm about as techno savy as the plunger you use to unstop a toilet. Thanks

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rbrandenstein
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Re: Monroe Mahalini

Postby rbrandenstein » Tue Nov 01, 2016 1:23 pm

While I beveled the bottom slots for the keel and battens, I did not on the sheer and chine slots. They were trimmed up when the pieces were attached. There is a minor amount of adjustment and you could use a chisel or multi-function tool. You could also tweak the ends of the chine and sheer to fit what you have.
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Bob
Completed Malahini (launched 6/24/2012)
http://bobsboatbuild.blogspot.com/

PeterG
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Re: Monroe Mahalini

Postby PeterG » Tue Nov 01, 2016 2:35 pm

Bob had the best approach, you can cut the notches for the chines and shears but not bevel them at this time. You can final trim the notches with a sharp chisel when you are installing the chines and shears. I suggested to bevel the sides at 13 degrees too, but in reality the bevel will eventually be less. I am not at the point of fairing yet, but in laying it all out on paper and plywood, the bevel on the sides will vary from roughly 5 degrees at the chine to about 9 degrees at the shears. The 13 degree bevel guarantees enough transom material to fair the sides to the transom AND it only requires one angle setup on your saw. I cheated and used my circular saw on the bottom transom edge, using a straight edge and the saw set at 13 degrees. I used a jigsaw for the sides and top edge.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Thompson
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Location: Monroe, Ga

Re: Monroe Mahalini

Postby Thompson » Tue Nov 01, 2016 6:06 pm

Thanks for the information. Cut my bottom with a straight edge and circular saw also. Trying to fix my transom before I resort to building a new one. Epoxyed a strip to the bottom tonite. Also was able to bend a piece of 3/8 white oak to a side piece. I'll try epoxying it tomorrow night. Can't use any fastners, they'll get in the way of fairing. If the epoxy holds i figured i could use longer screws when attaching the sides and bottom planking. Guess I'll get to see how good the epoxy holds. That piece of white oak was in a strain bending around the side piece. Thanks again for all the help.
Lyman

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hoodman
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Re: Monroe Mahalini

Postby hoodman » Wed Nov 02, 2016 4:13 am

The epoxy will hold. I don't see a problem adding strips when using epoxy. The planking fasteners are long enough to go through the strips especially after fairing. On the Geronimo Glen calls for 1 1/4" screws for the planking along the transom edges. Malahini also?

Thompson
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Location: Monroe, Ga

Re: Monroe Mahalini

Postby Thompson » Fri Nov 04, 2016 7:24 pm

Well. Epoxy didn't hold completely. Strips on sides came loose. Left some of the strip in place. Actually tore the wood apart. So I've already cut new frame pieces. I'll need to get another sheet of plywood. Might be able to use some the old transom for seat parts or something. Started putting some of the other frames together.

PeterG
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Re: Monroe Mahalini

Postby PeterG » Mon Nov 07, 2016 10:37 am

Sorry that didn't work out for you, was hoping it would. I spent as much time/effort with the transom alone as I did with the four frames and stem combined. Here is my transom assembly, pre-fabricated as much as possible to simplify the work to be done before the flip. I wanted any attachments to the transom to already be in place so that after I flip the hull I don't have to drill through the fiberglassed and painted hull. This was prior to final glue-up and drilling for the transom knee bolts.
20160924_215000b.jpg
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

Thompson
Posts: 41
Joined: Tue Sep 13, 2016 11:34 am
Location: Monroe, Ga

Re: Monroe Mahalini

Postby Thompson » Tue Nov 08, 2016 7:04 pm

Thanks for the information. I like the idea of prefabricating as much on the transom before the flip for the reasons you stated. Not sure I'd have thought of that.

Another question. The plans call for the motor well sides to be 33" apart and attached to the sides of the bottom battens. If this doesn't line up with the bottom battens, respace the battens or add another batten. On the pattern for the bottom the battens a evenly space. The motor well side lands on top of the batten so adding one doesn't seam right. Make one space larger and one smaller??? Or make motor well wider so the side lands on the batten. Or? Is there something I'm not seeing.

I've a!ready messed up one transom, I don't want do it again.

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rbrandenstein
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Re: Monroe Mahalini

Postby rbrandenstein » Tue Nov 08, 2016 7:50 pm

I would leave the battens sized and spaced per plans.
You can screw and glue another board on top of the existing battens to mount the plywood at the spacing you want.
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Completed Malahini (launched 6/24/2012)
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