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Old 21 January 2010, 09:52   #1
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prop upgrade for tohatsu

hi, does anybody know if you can change the prop on a 18hp tohatsu 2 stroke (2007)to obtain a bit more speed for towing inflatable toys etc. i have a bombard aerotec 380 and was thinking of upgrading the engine to 25hp 2 stroke. my only worry is the weight difference as we transport the boat and engine in the car, also i dont think my back would take the strain. does a stainless steel prop perform any better or is it just the pitch. many thanx.
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Old 21 January 2010, 10:23   #2
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Originally Posted by uny1965 View Post
hi, does anybody know if you can change the prop on a 18hp tohatsu 2 stroke (2007)to obtain a bit more speed for towing inflatable toys etc. i have a bombard aerotec 380 and was thinking of upgrading the engine to 25hp 2 stroke. my only worry is the weight difference as we transport the boat and engine in the car, also i dont think my back would take the strain. does a stainless steel prop perform any better or is it just the pitch. many thanx.
It may be possible to improve performance via your prop - but really you need to know:

Current prop size.
Current max revs at wide open throttle.
Max recommended revs for engine.
Gearbox ratio for engine.
Current max speed at wide open throttle.

Is it really speed you are lacking or acceleration?
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Old 31 January 2010, 05:32   #3
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Originally Posted by uny1965 View Post
hi, does anybody know if you can change the prop on a 18hp tohatsu 2 stroke (2007)to obtain a bit more speed for towing inflatable toys etc. i have a bombard aerotec 380 and was thinking of upgrading the engine to 25hp 2 stroke. my only worry is the weight difference as we transport the boat and engine in the car, also i dont think my back would take the strain. does a stainless steel prop perform any better or is it just the pitch. many thanx.
A stainless-steel prop will only increase performance by 2-3mph WOT, although your pitch selection will determine your hole shot (in terms of initial accelleration). A 25hp 2-stroke will give you more power on demand with a standard aluminium prop. Weight-wise it's around 50kg. More awkward to carry than outright heavy. If you have the space to store, a trailer might be the way to go so you don't have to dismantle and reassemble. Even a small box trailer is easier than lugging out of the boot of your car.
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Old 10 May 2010, 15:45   #4
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18hp should be ok for pulling toys around.

you dont need masses of speed, 15 mph is well good enough for ringos.
so i would be looking at the smallest pitch p[rop for the engine before worrying about upgrading.

as long as the toys get on the plane youl be ok



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