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Old 26 March 2014, 16:39   #1
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Transom mods aerotec 380, Pictures

Some pictures of the transom height mods I've done to the areotec. Two heights for two different engines, 25mm for the mercury 15hp and 50mm for the Johnson 30hp. With the engine sat in-between the plate it can only go in one place so centralizes the motor every time. Have used 8 of the 9 same screw holes in the transom so its not laced with holes.
Just need to got 2 bolts to finish it off.

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Old 26 March 2014, 18:11   #2
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Quote:
With the engine sat in-between the plate it can only go in one place so centralizes the motor every time.
That's a good idea.
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Old 26 March 2014, 20:14   #3
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BAC,

Are both engine's shafts lenght different size ? One is short, other is long ? Or both are same size and have been experiencing back or over transom water splashes ?

Happy Boating
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Old 26 March 2014, 20:43   #4
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Be careful dude, there are lots of risks when extending your transom.

Just be absolutely sure that your mod can take the force of your outboards...

Make sure that you get it checked before you use it
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Old 26 March 2014, 22:28   #5
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How does the boat run with the 30hp? What shaft length is it?

Thanks.
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Old 27 March 2014, 14:39   #6
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Both engines are short shaft, 30hp being about 12mm longer and the cavitation plate about 20mm lower. Engine is also about 17kg heavier than the mercury.

Having only done a trial run with the 30hp (which is pretty quick ) with the same lose 25mm block of wood I use with the 15hp I knew it needed to be higher and more substantial. 50mm being the highest I am willing to lift the engine up.

Having looked at other peoples examples of how they have extended the transom for the same reason of the water fall effect over the top I think this should work just as well.

I'm very aware of the problems of extending the transom and have no intentions of losing an engine or damaging the transom. As there were no off the shelf thumb screw plates big enough I've made one up out of 10mm marine grade alloy, this should spread the load.

Main test will be Easter holidays up Windermere, all being well will report back with the results.
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Old 27 March 2014, 16:24   #7
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While I dont think the 30hp will be a problem, its not the strength of the transom itself that people are concerned about.

Because of the extra height, you have increased the leverage force that the engine exerts on the places the transom joins the boat.

The concern is that the engine will simply rip the transom off the boat.

Zodiac glue of a certain age has a habit of failing antway, just keep an eye on all the transom glue joints to avoid any nasty suprises.
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Old 18 April 2014, 17:21   #8
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Results from transom mods on aerotec

All went well with transom lift mods, only tried with the Johnson 30, as have been using a 25mm block of timber on the Mercury 15 for the last year and I know that works.
The height seems spot on as the cavitation plate was level with the water when on the plane either one up or loaded. No water fall effect back into the boat or a mass of spray behind the boat.
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Old 18 April 2014, 20:25   #9
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What's the use of counting with 2 engines ? A 15 HP is a poor performer for a 380, why don't you just stick with the 30 and make a SS engine mount of same height and mount it direct on transom.

If sib is fully inflated to its working stated pressure, won't rip anything. What stresses transom side holders is running with a underunflated sib along max stated HP engine on choppy, wavy sea cond.


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Old 19 April 2014, 05:01   #10
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Id argue that a 15hp is almost optimal for a 380 for most people. I have an 18hp and it flies, very capable little set up and light enough to make it easy to carry. A 30 must make it into a right torpedo, and I guess you must be trailering the boat or have a mighty spine.

The transom mod is really interesting - thinking of doing something similar myself due to excessive splash
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