Reply
 
Thread Tools Search this Thread
 
Old 21 January 2010, 14:52   #1
Member
 
Country: UK - England
Town: stockport
Length: 3m +
Join Date: Apr 2009
Posts: 49
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.
__________________
uny1965 is offline   Reply With Quote
Old 21 January 2010, 15:23   #2
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,627
Quote:
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?
__________________
Poly is offline   Reply With Quote
Old 31 January 2010, 10:32   #3
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 70hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 4,645
RIBase
Quote:
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.
__________________
spartacus is offline   Reply With Quote
Old 10 May 2010, 20:45   #4
Member
 
phillnjack's Avatar
 
Country: UK - England
Town: slough
Boat name: not named yet
Make: Orkney Dory 4 metre
Length: 4m +
Engine: outboard evinrude 60
Join Date: Sep 2009
Posts: 80
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



phill
__________________
phillnjack is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 16:59.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.