Free Boat ... Not so Free!

[KevFroehlich]

New to the boating world; received free boat to refurbish - 15hp Evenrude 2 stroke. Had a Solas 3 blade prop - sent to install a new rubber hub assembly but, the machine shop cracked the aluminum trying to press the rubber hub. They replaced the prop with a "Michigan Match" 3 blade prop. The only difference is the Solas was a 9.25 x 10 and the MM is a 9.50 x 10. Does anyone know the differences - if any?
Any feedback would be GREATLY appreciated!

 

[82rude]

Re: Free Boat ... Not so Free!

actuall zero diff.solas uses 9.25 dia on their props for the 9.9 to 15 and michigan uses 9.5 .dont sweat it ,its kosher.

 

[82rude]

Re: Free Boat ... Not so Free!

also want to learn a little about props etc look part way down these pages and they have little tutorials about props.

 

[jestor68]

Re: Free Boat ... Not so Free!

The difference is only 1/4" diameter; which will make only a small measurable difference in performance.

Different manufacturers will often make props of the same pitch with slightly different diameters. Since a change in diameter also affects the performance of a prop, to have a selection of different diameters in a given pitch size offers greater ability to "fine tune" the performance of the motor.

The other difference(in this case) is that the Solas is a better performing prop due to it's more up to date design and method of casting.

 

[Silvertip]

Re: Free Boat ... Not so Free!

The difference is only 1/4" diameter; which will make only a small measurable difference in performance.

Different manufacturers will often make props of the same pitch with slightly different diameters. Since a change in diameter also affects the performance of a prop, to have a selection of different diameters in a given pitch size offers greater ability to "fine tune" the performance of the motor.

The other difference(in this case) is that the Solas is a better performing prop due to it's more up to date design and method of casting.

Props are designed for the specific range of engines on which they will be used so diameter is a limiting factor that must be considered. Prop diameters change within a given engine-specific range because of other design characteristics such as rake, blade shape, pitch etc. They do not design props to be 1/2 or 3/4 inch different just to offer a different diameter. Within a given engine-specific range as pitch goes up, diameter comes down and vice versa. That accounts for the slight difference in diameters. The same prop characteristics from different manufacturers will likely perform differently. It all depends on the "design" of that prop and what performance characteristic(s) the manufacturer are designing the prop for. Of two seemingly identical props, one may have a better hole shot than the other -- or perhaps the one with the lesser hole shot has a higher top speed. It is all about "design" -- not just about 1/2 difference in diameter.

 

[gm280]

Re: Free Boat ... Not so Free!

I'm sure this guy has no knowledge of all the prop parameters involved and seriously could care less as well. The bottom line is he will basically see ZERO difference with his setup...period. Now if he was running some high performance hull design and an equally high performance engine, then yes all those intricate prop parameters do affect the actual boat performance. After studying prop design and theory, I have come to the conclusion that even two props from the exact same mold can have slightly different performance levels...that is how finicky prop design/parameters can be in certain hulls... But being able to actually measure that difference takes some expensive equipment. Bottom line on this situation is he will be a-okay...no problems!

 

[saumon]

Re: Free Boat ... Not so Free!

Your title remind me of the funniest one-liner ever said in the boating world, which is "I've got a free boat"! :lol: