please explain difference

[fbinker]

just bought a used 1998 mariah 180 4.3 2 barrel alpha 1 stern drive has the stock propeller on it which I think is a 143/4 19p. will be pulling kids on tube & waterskies. Looking for fast plain with good speed. the mercury tech I had work on the boat told me to go to a stainless prop, would gain 4-5 miles per hour. I found a 5 blade stainless 131/4 20p part number 48-816612A4520P would this be a good choice. Any comments would be great. Thanks

 

[bhammer]

Re: please explain difference

First, what WOT are you running now?

Generally, when you increase blades, you decrease in the pitch to maintain the same WOT. I am not sure though as you are dropping an inch in diameter. I would think going up to a 20P will not help with the hole shot. Maybe go down to a 17P 5 blade. It's hard to tell without knowing your WOT. The prop experts will have more to say.

 

[bhammer]

Re: please explain difference

And there I go again with my manners..... Welcome to iBoats. Lots of good folk here.

 

[fbinker]

Re: please explain difference

I'll try to get out on the water this weekend and find out the top speed. will also check rpm at WOT. Just bought the boat two weeks ago. did have it out today but also had 2-4 foot waves and was only 42deg. thanks

 

[bhammer]

Re: please explain difference

Have fun and let us know. I am sure someone here will be than helpful.

 

[freddyray21]

Re: please explain difference

in general the lower the pitch the better hole shot and the higher the pitch gets you a slower hole shot but more speed. the reason for stainless over alum is that the stainless will have less to zero flex and be more efficient. However, with stainless if you get into some rocks it won't give and the damage is usually to the outdrive rather than the prop if the hub does not protect you. I run aluminum as I have been know to get into the rocks. I am running a 17 pitch on my 120 hp Mercruiser and find it tachs out just right with a good hole shot.

 

[steelespike]

Re: please explain difference

If your thinking stainless save some money and check out the Turning point props.Close to stainless performance at Aluminum prices.
We need to know your present max rpm and speed.By gps if possible.
And are you sure of the prop size?Any prop change is a bit of a gamble.
The right prop will deliver more performance assuming your not at the top now.Increase could be as little as a few tenths of a mph.If you end up with the wrong prop you've wasted your time and money.
The 5 blade is over kill.Generally a 4 bld will deliver better low end performance at a slight cost of top end.