Prop size for TomCat

S

squidslayer

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C Dory Year
2007
C Dory Model
255 Tomcat
Hull Identification Number
Hull # 70
Vessel Name
ShirleyMae
I got Honda 150's on my Tom Cat with S 3X15X19L Stainless Steel Props
I would like to get more torque in the low RPM's Out here off SF the swells can get BIG and if I happen to be out in them I would like to get a little more hill climbing power. Are their any other TC owners Honda 150's that run different props than what I have? I was thinking of going to a 3X 15X 17 prop
What would be the trade off in performance?
Any input who be appreciated.

DickE
 
We are using 3 blade stainless 13 X 17 Honda props on the Honda 135 HP. I am satisfied, but have not tried anything different.

Brent
 
Dick , the 17s will make a big difference for hole shot and acceleration . Those hondas dont make their power till the V tec kicks in at about 4400 RPMs . Just dont run them over 6k and you will be fine .
Marc
 
Just for contrast, we have a Honda 150 on Journey On, a monohull. At present there is a 15" pitch propeller on the engine. When I change to a 16" pitch, there is a noticeable effect on the engine in that it revs slower. You're running 19" pitch on a catamaran (with 2 engines) so obviously you need far less thrust at the lower speeds and are saving the power for when you're going fast. Much faster that I go on Journey On.

Boris
 
The question I would ask is what is your WOT RPM currently, and the speed at WOT. Most likely you will do better with the 17's.
 
Wide open with the 3X 19s the highest rpm I believe I can go is about 5400rpms@ 37 mph
I think I am going to put on Some Honda 4 blade 17s aluminums for a trial run. The shop says that 4 blades will help also with low rpm torque

Thanks
DickE

quote="thataway"]The question I would ask is what is your WOT RPM currently, and the speed at WOT. Most likely you will do better with the 17's.[/quote]
 
Marc, Matt -- I want to buy a set of backup props for my cruise this summer. Probably aluminum, possibly the Piranha that I believe Roger uses on Dreamer. What size should I get for my 150 Yamahas and do they make counter-rotating versions? Would they be the same size as what folks use on 150 Hondas?

Thanks,
Warren
 
Warren, You probably have 19s on the boat now as I remember . I would go with aluminums as spares and you can get them as counter rotators . When I was on your boat it performed very well and I would stick with that pitch . I am not a fan of plastic props except on movie sets, sushi bars and in window box fans .
Marc
 
If you have SS props on now, the Aluminum props will flex more, and the sized down will seem to be more than the 2". Also generally the 4 blade prop will give more stern lift, and a slightly lower planing speed. Four blades may not necessarilly give you more low end performance. There are many factors in prop design, including cup, rake as well as pitch and diameter. Some times it is trial and error. It will be interesting to see what the RPM and speed does. If you can deal with a place which will loan the props until you have it dialed in correctly.

The Suzuki outboards have a different gearing, and use a much higher pitch prop--plus a slightly larger diameter--and most of us get a higher speed out of the boats.
 
Wefings":2pzgfcxt said:
Warren, You probably have 19s on the boat now as I remember . I would go with aluminums as spares and you can get them as counter rotators
Click to expand...

Marc -- Thanks for that info. I was hoping someone could also tell me what the "usual" pitch is for 19" props, for my engine, so I know what to order.

thataway":2pzgfcxt said:
If you have SS props on now, the Aluminum props will flex more, and the sized down will seem to be more than the 2". Also generally the 4 blade prop will give more stern lift, and a slightly lower planing speed. Four blades may not necessarilly give you more low end performance. There are many factors in prop design, including cup, rake as well as pitch and diameter. Some times it is trial and error. It will be interesting to see what the RPM and speed does. If you can deal with a place which will loan the props until you have it dialed in correctly.
Click to expand...

Bob -- I am not looking to change the performance of the boat. As Marc says, it is running well with the SS props. I just want to take a spare pair to Alaska with me, and am trying to find out what I should order.

Warren
 
Bob& Marc

You said that we Alum 4 blade17's "the sized down will seem to be more than the 2".

Do you mean the the alum 17's will actually perform like 15's??
my dealer is willing to let me try them out
Talked to a gent yesterday that has twin hondas on his heavy Cat...he told me he likes the big seas performance of 15's on his cat best
Do you think 15's are to low??
thanks

DickE


thataway":2msmtiap said:
If you have SS props on now, the Aluminum props will flex more, and the sized down will seem to be more than the 2". Also generally the 4 blade prop will give more stern lift, and a slightly lower planing speed. Four blades may not necessarilly give you more low end performance. There are many factors in prop design, including cup, rake as well as pitch and diameter. Some times it is trial and error. It will be interesting to see what the RPM and speed does. If you can deal with a place which will loan the props until you have it dialed in correctly.

The Suzuki outboards have a different gearing, and use a much higher pitch prop--plus a slightly larger diameter--and most of us get a higher speed out of the boats.
Click to expand...
 
DickE; I don't think you can predict what the performance will be until you try those specific props. I would try the 4 blade 17's and see how they work. I don't think they will be exactly like 15" SS props. But you may get a few more hundred RPM than you expected--which would be fine, as long as you don't exceed redline. I have run more aluminum props on outboards than SS props. It just happens that currently I have SS props on both of my boats.

Warren; The aluminum are great as back up props--and what I always carry. With any luck you will have no problem at all, but it always is a good idea to carry a spare set of props, with extra pins, cotter keys, thrust washer and prop nut etc.
 
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