Malahini Transom Angle

Questions about modifying a design

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Stromz
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Malahini Transom Angle

Postby Stromz » Sun Oct 23, 2016 1:23 pm

My transom drawing does not show a double line at the bottom. Technically if there's an angle I would think the drawing would show it. SO, before I make the cut I wanted to check in with Team Glen-L builders. Do I follow protocol and cutout the transom per the drawing, angle the transom and then cutout the 0.159" for the bevel? Or do I add 0.159" (at the bottom) to the drawing and then cut out the transom frames? I'm leaning towards cutting per the drawing. I'm also assuming I'm looking aft at the transom drawing but not sure it matters.

Note: DSR commented that his drawing for his design shows a double line at the base of the transom representing the 12 deg bevel. My drawing does not show that. If it did the confusion wouldn't be there.

Stromz
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Re: Malahini Transom Angle

Postby Stromz » Sun Oct 23, 2016 2:12 pm

I think I have the answer - thank you DSR! The book states the full size pattern drawings are to the back of the transom. If that's the case then I will need to add 0.159" to the bottom outer 3/4" ply, 0.319" to the bottom of the frames, and for my 3/4" ply onto the frame on the inside...that bottom will extend by 0.478".Please let me know if I'm on the right track.

Note: I took the Tangent of 12 deg and then multiply by 3/4" for the outer ply. For the frames the multiplier is 1.5", and the inner 3/4" ply would be 2.25".

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rbrandenstein
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Re: Malahini Transom Angle

Postby rbrandenstein » Mon Oct 24, 2016 6:58 am

Stromz,
I think you are on the right track. The plan dimensions are to the outside of the hull and don't account for material thickness, which you must consider. While the transom is 12 degrees from vertical, it is actually 13 degrees from the the keel, since the keel is not level. (The keel rises slightly from the transom to frame 2)
It is not too critical to cut this angle accurately as long as you leave enough material. Once mounted, you will fair the hull and edges of the transom to create the correct angle.
Transom.jpg
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Bill Edmundson
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Re: Malahini Transom Angle

Postby Bill Edmundson » Mon Oct 24, 2016 7:23 am

Stromz

Bob's right. Just cut it "fat". You can fair it perfect later. I think the Malahini has some deadrise. That makes even more of a task out of cutting it right up front.

Bill
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Stromz
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Re: Malahini Transom Angle

Postby Stromz » Mon Oct 24, 2016 10:10 am

Thanks Bill and Bob. Sounds like if I cut everything fat then perhaps I should leave the outer ply off until I get the bottom beveled and battens in place since the battens butt up to the outer ply? I'm thinking that carving out for the battens with the outer ply bonded to the frame would be a pain. Would you agree? And am I hearing correctly that the transom angle is 13 degrees and not 12 degrees due to the keel rising slightly? I missed that one and will go back and review the drawings. Thank you for the headsup.

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chugalug
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Re: Malahini Transom Angle

Postby chugalug » Mon Oct 24, 2016 10:22 am

:D This little gizmo works really good for carving out for battons
IMG_0766[1].JPG
good for glue clean-ups too :D
Working on regular-sized Bo-Jest


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Bill Edmundson
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Re: Malahini Transom Angle

Postby Bill Edmundson » Mon Oct 24, 2016 10:49 am

The keel rise is often not called out. But, it is there. If you put a straight edge on the plans on a horizontal line you can see it.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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Stromz
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Re: Malahini Transom Angle

Postby Stromz » Mon Oct 24, 2016 12:44 pm

chugalug wrote::D This little gizmo works really good for carving out for battons
IMG_0766[1].JPG
good for glue clean-ups too :D

I'm interested. Please tell me more. What is it? How does it work? And would it carve out a batten slot with the back transom ply in position without hacking up the back transom ply?

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rbrandenstein
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Re: Malahini Transom Angle

Postby rbrandenstein » Mon Oct 24, 2016 2:55 pm

The 12-13 degree comment is in the instruction sheet for the Malahini.

Making the transom frame and attaching, and then mounting the plywood would work. Yes, the battens stop at the transom.
I angled the bottom of frames at 13* and then made repeated cuts at the keel and batten locations on my table saw with the blade height set to the correct thickness, holding the frame piece at the angle. That put the correct angle on the cut. I then completed the transom frame and aligned and fitted to the form. Then I mounted the transom to the frame.
Here is the transom frame getting aligned and positioned. You can see the cuts for keel and batten as well as chine and sheer.
IMG_0328.JPG
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hoodman
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Re: Malahini Transom Angle

Postby hoodman » Mon Oct 24, 2016 3:04 pm

Go ahead and cut the notches for the battens before you glue up your transom. Don't worry about the angle. You can either dial it in with a chisel or with one of those oscillating multi-tools when you get ready to install your battens. I went with a chisel because that's what I have.

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chugalug
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Re: Malahini Transom Angle

Postby chugalug » Mon Oct 24, 2016 11:00 pm

:D The little blue tool is an oscillating tool(kinda vibrates from side to side)doesn't cut very fast but it does cut-coarse I was using it in oak)might be faster in mahogany.I got it from local hardware store.regular price was 29.95 for kit(got this one on sale for 19.95)Kit includes tool,sanding attachment with lots of sand paper(hook and loop)cutting blade and allen wrench to change out blades as well as carry bag.
Working on regular-sized Bo-Jest


"If it's not crooked,It's not mine


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