Right prop?

[homey55]

I have a 1973 18' fiberglass low profile skiboat with a '73 Merc 1150 motor. Currently I have a 487734G A40 19p prop. I run about 4800rpm @ 38mph (GPS). Is this the right prop? Used to be used as skiboat, now using for fishing. Don't really need to get out of the hole but would like more speed if possible. Should I change props? If so should I go up or down in pitch? This confuses me. Thanks for your help. Also, any recommendations as to where to order props?

 

[Bear]

Re: Right prop?

Was both engine and boat used as a skiboat with this propeller? I seems to be to high pitch for a skiboat.<br />Rpm range is 4800-5300 for a 1973 1150. A 17" pitch will give you more rpm, a better hole shot perhaps more speed too (in this case).<br /><br />Not sure but I think you have a 13" x 19" <br />Try either a 13" x 17" or 14" x 15" <br /><br /> http://www.maxrules.com/oldmercs/Propellers/Props/20.PDF

 

[homey55]

Re: Right prop?

yes, It has always been used as a skiboat. Seems the old man had two props, a 19 and 21?? Don't remember. You recommend I try a 17? This will give me more speed and better "out of the hole". I always thought you had to sacrafice speed for pulling a skier? Though since I will be buying a 2nd prop, I should get the right one. just fishing, Too old to ski anymore.

 

[Bear]

Re: Right prop?

Sometimes when you are overproped you can gain some speed if you lower the pitch. Usually you can't have both holeshot and top speed. <br />Lower pitch better acceleration, lower top speed, burns more fuel and a risk for over revving.<br />Higher pitch slower acceleration, higher top speed burns less fuel. But if you have too high pitch you can go slower at wot (wide open throttle) because the over all ratio is too high.<br /><br />If there was a 21" propeller too there is something I don't understand. Did he ever use it?<br />A lower diameter

 

[Dhadley]

Re: Right prop?

If I read this correctly you are looking for more speed and maybe some more rpm's. As long as you hace a good baseline on the 19" prop try raising the motor a hole or two. That should increase top speed, top rpm's and help with the holeshot. <br /><br />Post that info and we can go from there!

 

[leebob]

Re: Right prop?

Do you have a jack plate ,In the past I have had simular problems with this situation a jack plate gives you a lot of options on how to set up your motor ,when you raise the motor it seems to pull more of the boat out of the water a gain a little speed ,as far as props go I am lost ,I will probally have a post on mine about props once I get it running right (maybe this will help)..LEE