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Old 22 January 2016, 21:53   #1
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Transom cutting question

Hi guys, I am about ready to start the heavy work on my project, a 22' Zodiac Hurricane 630. This came with a diesel inboard. I removed the motor and had the old hole in the transom patched up.

I was going to do an outboard bracket but ran into a problem with the bracket company. Now I am about to order one from another fabricator but had a random thought: cut down the transom to fit a 25" shaft outboard.

Is this taboo or totally acceptable? I think structurally it should be fine. Thick transom supported by a pair of large knees. The area will also be reinforced by glassing in a floor straight to the transom. My last ribs had low transoms so I am not worried about water splashing over the top; I actually prefer being able to reverse quickly to flood the deck and wash off the fish blood etc.. That's one of the reasons I thought cutting the transom would be ideal. The other reason is to keep the overall length down.

The original water line at rest, with the old 450+ kg inboard setup, is where the blue line is drawn. The black lines show what it would resemble if I cut out an area for the outboard. Thanks fellow ribbers!
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Old 23 January 2016, 03:50   #2
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Personally, & this is purely my opinion, I'd avoid cutting the transom like the plague. I don't think strength would be an issue, unless you cut into the "patched" area where the outdrive penetrated the transom. I think you will end up with a very wet boat, also any outboard engine sat there will be very low in the water, the water will be lapping under the powerhead.


Just my 2 penneth.
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Old 23 January 2016, 04:48   #3
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Difficult to say without actual dimensions but TBH doesn't look too bad. If I were going for this option though, I'd seriously consider fabricating an engine well to restore the freeboard integrity.
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Old 23 January 2016, 05:03   #4
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I think you'll be fine - subject to the repair of the sterndrive aperture being good.

My boat only has about 6" freeboard at the outboard.

I would also think that the weight in the stern will be much less than the 450kg engine you've removed. Heaviest outboard is about 300kg?

What's the distance between your blue and black lines?
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Old 23 January 2016, 07:44   #5
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You should try searching previous threads for Hurricane 630 and 640 builds. I may be mistaken but I believe a member on here had cut down a H640 transom as part of an inboards to outboard swap. Keep in mind if you do cut it , it has to be wide enough to allow the motor to tilt side to side when in the raised position.
I am still undecided on my 640. Probably going with a jack plate rather than a bracket. The bracket would push my length into a larger dock slip which significantly would raise my annual dock slip fee.

Good luck and keep us posted!
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Old 24 January 2016, 04:57   #6
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Quote:
Originally Posted by Pikey Dave View Post
Personally, & this is purely my opinion, I'd avoid cutting the transom like the plague. I don't think strength would be an issue, unless you cut into the "patched" area where the outdrive penetrated the transom. I think you will end up with a very wet boat, also any outboard engine sat there will be very low in the water, the water will be lapping under the powerhead.


Just my 2 penneth.
I agree with PD!...on the pics that's a hell of a lot of material to loose from one of the most structurally important part of you're boat!..and could open a can of worms from potential transom failure,to re-sale implications.
It can be done on certain models,but really do you're home work and double check with people who have done the exact same modifications your on about.
(See below)
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Old 24 January 2016, 07:06   #7
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You wouldn't cut the transom, you'd add an engine bracket off the back?

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Old 24 January 2016, 09:11   #8
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This is a factory transom height on an outboard version. Much lower than tworotors I/O version.
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Old 24 January 2016, 09:21   #9
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That looks very low, my transom is around 3/4 way up the tubes.
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Old 24 January 2016, 09:24   #10
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This is a factory transom height on an outboard version. Much lower than tworotors I/O version.
that looks like it has a "bulkhead" a few feet in front of the transom though?
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