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Old 09 August 2012, 06:27   #1
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Country: UK - Wales
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splash back!

I'm running an 18hp tohatsu short shaft on the back of my 4.2m zodiac classic mk2.
When opening throttle more than a gentle cruise, I get a heap of splash back coming over the transom - from the leg of the tohatsu

The pin is in the 2nd hole up, although there is no difference if in the 3rd up, boat loaded with 80% of weight forward (1 person and kit)

Any ideas how to stop with annoying splash?
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Old 09 August 2012, 06:46   #2
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This happened when i used to have my old small zodiac with a 5hp. i bought the engine height (not the trim) up a little which helped reduce it alittle. Might work for you too
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Old 09 August 2012, 07:51   #3
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It's been reported here before and seems to be common - raising the engine on the transom helps a little. Someone (mchappelow?) fitted a homemade "splash guard" on his which he said was a big help.
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Old 09 August 2012, 09:55   #4
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Make: Sea Rider Boats
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Quote:
Originally Posted by SiClapham View Post
I'm running an 18hp tohatsu short shaft on the back of my 4.2m zodiac classic mk2. When opening throttle more than a gentle cruise, I get a heap of splash back coming over the transom - from the leg of the tohatsu :Any ideas how to stop with annoying splash?
Tohatsu's are prone to spash issues as described when engine is not height seated correctly on transom, it's a tail design issue. You could play with trim holes all day long with no aval. By the way, what's your transom middle height to lower hull/keel ? Is it less than 40 cm height ? To correct check following link under last post, just follow same procedures.

Cavitation problem with new engine

Happy Sibbing
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Old 09 August 2012, 12:11   #5
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I get a wonderful cock tail in my 4.2 futura with a 20 Yamaha short shaft when doing over 18 kts, but very little comes back into the boat. Are you running a long or short shaft?
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Old 09 August 2012, 14:14   #6
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Country: UK - Wales
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Quote:
Originally Posted by Locozodiac View Post
Tohatsu's are prone to spash issues as described when engine is not height seated correctly on transom, it's a tail design issue. You could play with trim holes all day long with no aval. By the way, what's your transom middle height to lower hull/keel ? Is it less than 40 cm height ? To correct check following link under last post, just follow same procedures.

Cavitation problem with new engine

Happy Sibbing
Right, my transom is 37cm and some packers are cut for try-out tomorrow; bringing it up to the 40cm ish.
I'll post the outcome on here tomorrow evening

Thanks
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Old 09 August 2012, 14:15   #7
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I get a wonderful cock tail in my 4.2 futura with a 20 Yamaha short shaft when doing over 18 kts, but very little comes back into the boat. Are you running a long or short shaft?
It is a short shaft and an upgrade from my old johnston......which never suffered this annoyance; but then it never went this fast either
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Old 09 August 2012, 18:51   #8
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Originally Posted by SiClapham View Post
Right, my transom is 37cm and some packers are cut for try-out tomorrow; bringing it up to the 40cm ish.
I'll post the outcome on here tomorrow evening

Thanks
You need to shim rise that transom to be at least 40/40.5 cm height to work as expected. You could place a wooden shim screwed into transom to fill irregular shape so to have a straight transom. Probably will need to re position inside/outside motor pads height accordingly.

Happy Sibbing
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Old 10 August 2012, 02:51   #9
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This seems to be very common - if you consult the manual and see where the anti-cav plate should be in relation to the bottom of the 'hull' then the engine will be too low, this is certainly the case when checking my Tohatsu 9.8 on my Zodiac 3.4m in the garage. Problem is the engine cannot be raised more than 20mm as the clamps will then not sit right against the transom plate.
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Old 10 August 2012, 04:09   #10
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This happened with my new 18hp Tohatsu just last week. A 1 inch block of wood under the clamps has significantly reduced splash back.
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