Anyone running a Solas prop on a Yamaha 8hp 4-stroke

ncpi

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I need to pick up another prop. My 2005 Yamaha F8MSHC came with a 8 1/2" x 7 1/2" prop. I have it on a 14' v-hull Lowe fishing boat (1462). I believe the 6hp came with the same prop. The Solas props are much less expensive but only come in a 7" or 8" pitch. I was thinking since the 6hp came with the same prop I could probably go with the 8 pitch and be OK. Anyone running one of these? what was your experience?
 

ncpi

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

Wow... nobody must be running a Solas prop
 

99yam40

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

that or not many run a F8
 

ncpi

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

that or not many run a F8

Yep...or running a long shaft on a sailboat which wouldn't be apples-to-apples and you probably never have to replace the prop.
 

jestor68

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

If your Yamaha came with a "Yamaha" prop on it, you are already running a Solas prop(a prop made by Solas). :)
 

steelespike

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

to do it right you should get an induction tach and check your rpm. A 7" will give you more power and rpm probably a little less speed.
if your present 7 1/2 is too much th 7 may help.
If the 7 1/2 isn't enough the 8 may help. If you could get us your gps speed that would help a little.
Does it get up quick and plane? Do you carry much weight normally? A 8 hp could probably run close to 20 on a light reasonably fast boat.
 

steelespike

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

to do it right you should get an induction tach and check your rpm. A 7" will give you more power and rpm probably a little less speed.
if your present 7 1/2 is too much th 7 may help.
If the 7 1/2 isn't enough the 8 may help. If you could get us your gps speed that would help a little.
Does it get up quick and plane? Do you carry much weight normally? A 8 hp could probably run close to 20 on a light reasonably fast boat.
 

ncpi

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

Sorry I didn't get this posted in the correct forum to start with. Thanks for moving.

Wish I had access to an induction tach, but give me a couple days to get it out on the water with at least a GPS and I'll post the data. Appreciate the help!
 

ncpi

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

Here's the info from running the boat today. It does run pretty well on the 8 1/2 x 7 1/2 stock prop. It takes about 8 seconds to plane with about 300 lbs of engine, person, dog and fuel on board which is about 53% of max loading. Boat empty weight is 180 lbs. Top speed is 17mph, per my GPS. There will be times I am loaded to the max if I have 3 people for a fishing trip, but speed would be less important in that case. Unfortunately, without a tach I really don't know what the RPMs are. Engine specs are 5-6000 RPMs.

Not sure if I go with a Solas prop if the 7" or 8" pitch would be better. I don't really need it to accelerate out of the hole faster and I don't really need more top speed. Where I go it can be pretty shallow, so speed is not always your friend.

Recommendations?
 

steelespike

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

A very rough estimate guessing a 10% slip using g 2.08 gear ratio 17 mph makes about 5500 rpm.
If the 7" prop takes you up to 6000 the speed will be about the same again thats guessing 10% slip.
The 7 will help with that heavy load as well.
An induction tach like the tinytach is about $45 and easy to install.Can be hand held or permanent
and it will work on almost any motor.
I don't see any real advantage for the 8" except possibly a touch more speed depending on the rpm it can make.
Slower to plane and will surely struggle with a load.
 

ncpi

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Re: Anyone running a Solas prop on a Yamaha 8hp 4-stroke

Very good points; I can see how you calculated 5500 RPM. Thank you very much for your effort, I really appreciate it. If the 7" will go to 6000 RPM (and not over) then it might be the best choice as you recommend. The max throttle output range is 5000-6000 RPM, but it shows peak HP (of 8) at 5500 according to the book. Looks like the factory did a pretty good job of matching the prop. I will have to research that tinytach and possibly buy one to see what RPM it is really running at WOT with the current prop as I wouldn't want to go above 6000 if I switch. I also agree the 8" pitch appears like it would take it down the RPM / Torque curve enough that it probably wouldn't put out peak HP. I think the only way the 8" would be better is if its currently slipping about 20% and the RPM is closer to 6000 with the current prop.
 
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