Tohatsu 6hp speed/prop

[Tommy c]

This is a follow up really to my 'planing' thread .
So I took my t32 out for it's maiden voyage.
As per title, I've got a tohatsu 6hp 4t
I was a bit concerned about performance 2 up but pleasantly surprised.
WOT I achieved 10 knots (10.5 max on the navionics app). This was on a freshwater lake.
The engine topped out at 5280 revs
I'd seen the YouTube video Erick Martin and that he swapped down to a 7" pitch prop from the factory 8"
Bearing in mind I will mainly be solo but 50/50 lakes and sea, would the swap to a 7" pitch be worthwhile
I'm totally clueless regarding props and their performance.
TIA

[Coniston]

I’ve been looking at this boat too, so interested in reply. No boat at present, but have a 2002 4hp two cylinder Johnson 2 stroke ….what value does it have? Was looking for a boat easy to transport for lakes with perhaps a very limited use on salt water eg Poole harbour. Mainly for one poss two. Was thinking a Yamaha 6hp following watching The Gurnard. Now retired so looking for a boat easier to use. Could also use on canals. Be really grateful for any thoughts, thanks.

[Steve509926]

Originally Posted by Tommy c

This is a follow up really to my 'planing' thread .
So I took my t32 out for it's maiden voyage.
As per title, I've got a tohatsu 6hp 4t
I was a bit concerned about performance 2 up but pleasantly surprised.
WOT I achieved 10 knots (10.5 max on the navionics app). This was on a freshwater lake.
The engine topped out at 5280 revs
I'd seen the YouTube video Erick Martin and that he swapped down to a 7" pitch prop from the factory 8"
Bearing in mind I will mainly be solo but 50/50 lakes and sea, would the swap to a 7" pitch be worthwhile
I'm totally clueless regarding props and their performance.
TIA

Hi Tommy, depends upon what you mean by worthwhile.
With my limited understanding of prop pitches, this is what I think:-
6hp 4s Tohatsu WOT RPM range should be between 5000 - 6000.
Dropping down to a 7" prop will increase the rpm by approx 200, so your WOT rpm is going to be roughly 5500
My assumption is that will probably increase your acceleration a little, you will get on the plane slightly quicker, your WOT max speed will probably be slightly slower and your mid range rpm (3500 cruising rpm) speed will be slightly slower - you will probably use a little bit more fuel.
I always carry a spare prop just in case, so if you buy a 7" and find it's not "worthwhile" you will have just in case to carry with you.

[Steve509926]

Originally Posted by Coniston

I’ve been looking at this boat too, so interested in reply. No boat at present, but have a 2002 4hp two cylinder Johnson 2 stroke ….what value does it have? Was looking for a boat easy to transport for lakes with perhaps a very limited use on salt water eg Poole harbour. Mainly for one poss two. Was thinking a Yamaha 6hp following watching The Gurnard. Now retired so looking for a boat easier to use. Could also use on canals. Be really grateful for any thoughts, thanks.

Hi Coniston and welcome.
It may be better to start your own new post re: what sib, so that it isn't just limited to those members looking at 6hp Tohatsu props. Think you'll get a greater response.