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Old 21 November 2008, 04:04   #1
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Transom extensions..

Hi all,
I've made a brief search in the forum but couldn't find exactly the cons/pros of the transom extensions. What do they do really? (apart from giving some additional space in the boat)

Do you think it is worth to have this kind of modification in a small rib like 4.20?
I've seen these kits from Stainless Marine and it looks very nice






Can you enlighten me a little please?

thanks again,
Memo
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Old 21 November 2008, 04:53   #2
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I think the main reason for them is to give more space in the boat, but what I can't figure out is really how much extra space you'll get - my old Yam overhung the inside of the transom by about 4" - the Merc I just fitted is even less intrusive - the Aux case takes more space when tilted up than the main! The engine takes negligible space!

Down side I could see to adding them to a 4-ish M boat is that will there be enough bouyancy in the tube ends to support it at rest? You arre moving potentially 100KG further outboard.... will also affect the handling. Also the extra leverage on a transom probably designed without a huge amount of spare capaciy (otherwise the boat would be disproportionately heavy).

My fuel tanks are far more of a space guzzler than any engine I've ever had on any transom!


I'll now hand over to the racing squad to expalin the performance / handling side of things.....
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Old 21 November 2008, 05:28   #3
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Where's Cookee when you need an explanation about setback etc?

Dare I suggest you look on boatmad.com where you should do a search for 'Jack Plates', transom bracket, or Set back.

The performance and race guys use them more than cruisers, however Codprawn does have one on his RIB.

Nasher
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Old 21 November 2008, 16:49   #4
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Increases setback, putting the prop into cleaner water away from the disturbances directly after the step of the transom.

Quote:
Originally Posted by memo View Post
Do you think it is worth to have this kind of modification in a small rib like 4.20?
No
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Old 22 November 2008, 10:35   #5
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I've always thought a sealed setup may add some bouyancy at the stern but as you pointed out it will shift weight for sure! I already have problems with weight distribution and you are right it's not worth the efforts
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Old 24 November 2008, 07:06   #6
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Quote:
Originally Posted by Nasher View Post
Where's Cookee when you need an explanation about setback etc?


Nasher
Here!

These brackets are used primarily for performance gains - if you move the engine back you can get it higher and move the C of G back, of course that works well on flat water, but going upwind you may then need a bow tank to hold the front down! Most boats are designed to not need them or they come with them as standard or even built in.

To sum up only worth it if you need to move the C of G and gain a small increase in performance. Certainly wouldn't recommend something like that on a 4.20 - have you seen the price of them?
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When a boat looks that good who needs tubes!!!
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Old 24 November 2008, 09:30   #7
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Oh yes, nice ones come with a spicy tag!!
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