transom

Outboard designs up to 14'

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greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

transom

Postby greg mc » Sun Nov 27, 2016 10:24 am

Hi everyone been a while back back working with my zip!!!!

im at the stage were im done with fiberglass and getting ready to paint bottom,

and just remember that they said back of transom and bottom needs to be 90 degrees is this really needed???? im know they do this for more speed or is there something else that it will affect?? thanks for any help on this!!

tell next time Greg mc

jplatou
Posts: 38
Joined: Fri Nov 27, 2015 6:43 pm

Re: transom

Postby jplatou » Sun Nov 27, 2016 10:39 am

IF I am reading this correctly, you are saying the transom is at a 90 degree angle to the bottom, vertical? It should be 12 degrees up to 15 degrees off vertical to allow trimming the outboard down to prevent porpoising.

greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

Re: transom

Postby greg mc » Sun Nov 27, 2016 12:35 pm

NO SORRY my build up with frame work is 12degrees im saying after fiberglass I rounded of the wood so matt would not get cut but then after expoxy and ive read to make the bottom of transom to bottom edge to almost a point or sharp edge!

JimmY
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Location: Brighton, MI

Re: transom

Postby JimmY » Sun Nov 27, 2016 1:43 pm

Yes, you should try to get a sharper edge to help avoid porpoising and help planing.

I've seen several builders clamp a board across the transom and just lay in thickened epoxy. Then remove the board and sand to shape.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

Re: transom

Postby greg mc » Sun Nov 27, 2016 2:15 pm

Yes that's what I've read and seen pic of just getting lazy and what to no if that important just don't see to many pic on here and was interested of what other have done


Greg thanks

BillW
Posts: 110
Joined: Sun Oct 05, 2008 8:03 am
Location: Seattle, WA

Re: transom

Postby BillW » Sun Nov 27, 2016 3:34 pm

Greg, it is important to make that trailing edge a sharp corner, with very minimum radius.

Also, take this opportunity (before paint) to check the aft 5 or 6 feet of the bottom, with a good metal straight edge.
You want it completely flat (fore and aft) with no "rocker" at all. Even 1/ 16 inch is too much.
Fix it now, if necessary, with thickened epoxy, while fixing the trailing edge.

"Rocker" is like a rocking horse under there, and it will cause the boat to ride like that. The opposite of rocker, called hook,
is also not good, but rocker is worse. Fix it now while it's easy, if necessary.

Bill

greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

Re: transom

Postby greg mc » Sun Nov 27, 2016 4:25 pm

thanks guys so even the sides need to but a sharp edge? could any body send a pic thanks Greg

rleete
Posts: 128
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Location: Rochester, NY

Re: transom

Postby rleete » Sun Nov 27, 2016 4:37 pm

Only what is at the waterline or below. Above the waterline, whatever you want.

greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

Re: transom

Postby greg mc » Sun Nov 27, 2016 4:48 pm

ahhh more work but hey its worth it been a good project!!!!!

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rbrandenstein
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Re: transom

Postby rbrandenstein » Sun Nov 27, 2016 9:27 pm

My understanding is that only the transom needs the sharp edge so that water leaving the bottom doesn't get turbulent due to cohesion on the rounded edge. I only sharpened the edge of my transom. I duct taped a board in line with the bottom and filled with thickened epoxy.
Here is a picture of the result after sanding.
IMG_0620.JPG
________________
Bob
Completed Malahini (launched 6/24/2012)
http://bobsboatbuild.blogspot.com/

ArthurVR
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Re: transom

Postby ArthurVR » Mon Nov 28, 2016 4:22 am

Looks great!

rleete
Posts: 128
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Location: Rochester, NY

Re: transom

Postby rleete » Mon Nov 28, 2016 6:44 am

rbrandenstein wrote:My understanding is that only the transom needs the sharp edge so that water leaving the bottom doesn't get turbulent due to cohesion on the rounded edge.


The sides certainly aren't as critical, but rounded edges under the waterline lead to turbulence and drag.

greg mc
Posts: 42
Joined: Sun Oct 18, 2015 6:46 am
Location: Earlham, IA.

Re: transom

Postby greg mc » Mon Nov 28, 2016 9:18 am

hope they came through I added some pic.
Attachments
damming the transom 001.JPG
boat 260.JPG


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