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Old 25 October 2015, 12:08   #11
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Country: Finland
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Boat name: SR 5.4
Make: Avon
Length: 4m +
Engine: Toh1 3,5 Yam 90/2S
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Tohatsu 2strokes 25hp and 30hp has the same weight(basically same engine), the long shaft was out of memory abt 52 kg. I had a 25 on my aerotec 420 and that was sufficient but no harm done to have little extra hp.
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fun on a boat is inversely proportional to size...sort of anyway
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Old 25 October 2015, 17:20   #12
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Quote:
Originally Posted by Landlockedpirate View Post
The OP's question was about weight,I know they are not exactly the same.

Was making the point that you can get Yam 30's that are similar in weight to a 20, but you can also get Yam 30's that are similar in weight to a 50.

Trust me, you dont want to try picking up a 3 Cyl 30 and sticking it on the back of your SIB.
Sorry, misunderstood! Yes you are right the 2cyl is considerably lighter than the 3cyl
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Old 26 October 2015, 08:29   #13
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sunsport

i have had a 20 yamaha on a aertoec 380 for 4 years plenty off power for normal use will pull waterskiers up to 13 stone have just recently fitted yam 30 3 cyl model this is not auto lube and is connected to steering and remotes not much weight difference but would advise remotes on the larger engine as it would be easy to flip with your weight and a heavy engine on the transom ,have been close a few times. superb performance with the 30 proper powerboat . but if i was not using the boat for skiing i would still be using the twenty ,either way do no not forget your kill cord as with both engines it is a superb power to weight ratio and you will get lots off smiles per mile ,happy boating
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Old 26 October 2015, 14:38   #14
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Thanks all!

I currently use a mariner 15 2 stroke on the boat and tbh its perfect 90% of the time. I believe it's just 34kg and is very easy to carry around. But if we are 4 up plus picnic tent etc we could do with a bit more va va voom. 1 up with a tiller controlled 30 HP would be interesting.
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Old 26 October 2015, 15:18   #15
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sunsport

the 380 does not accelerate onto the plane ,it launches itself ,my wife has skied behind it for years ,but the 30 tears the handle out of her hands unless you feather the power on.top end isnt much quicker but it gets there in half the time , dont let anyone put you off just be aware that the boat is at the upper limits on being safe, your only live once so enjoy.cheers
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Old 27 October 2015, 08:15   #16
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Country: Netherlands
Boat name: Commando C4
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Length: 4m +
Engine: Tohatsu 30HP M25C3
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I recently bought a mint 2003 Tohatsu 25hp two-stroke. It's a down-tuned 30hp. Can be easily converted to 30hp. Weighs 51kg.
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Old 28 October 2015, 06:16   #17
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Ok, a wee bit late here with my 2P's worth, but there is (as you have seen) no sweeping answer.....

Also for a given manufacture the "shared block" may change with model year.... E.G. the Johnsorude 25 sometime in the mid 70s went from being the same basic lump as the 20 to then being a de- tuned 30 (35?) and also got this new fangled thru' prop exhaust thing at the same time - and of course the new 25 Hp head wouldnlt fit the old leg....

The best thing to do is pull the specs for the engine you are looking at, then compare the CC & weight of the bgger / smaller lumps.

OTher thing to check is how easy a change is it? I upped a Suzy DT25 to a 30Hp by changing a throttle cam and a WOT stop on the middle carb! I have read threads in here about new exhausts , and even new ECUs (spark advance & the like type changes), so If you are serious about an upgrade do some reasearch or you may end up being cheaper just buying the bigger HP variant!

Boatinfo.no has a lot of useful reference material (and I think is run by someone on here?)
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