z.zuperboat

Ok if my rpm now is 5000 with the 1.68 going down to a 1.5 should bring my rpm down to say 4600 ? Using the same prop. I dont want to do gears and a prop change. The boat has run some good numbers now. But theirs always room for improvement !!

MOBILEMERCMAN

Z what are you running 100 102?
Jim

throttleup

If you are running a #6 drive or other drive that uses a diameter of 16", or larger, 35 pitch props are fine. Pitch is limited by diameter. A larger diameter prop can have a larger pitch.

Diameter is the limiting factor for pitch.

fastlane40

So is a 36 pitch prop inefficient with a 1:27 ratio?Because i am nearly there.

MOBILEMERCMAN

Haulin the mail. Twin engines often benefit from a tall pitch. Single engines on the other hand seems to me like less in their set up.
Jim

throttleup

That depends on what prop you are running.

A Bravo 1 36 is quite a bit smaller than marked. It's not uncommon to replace a 36 Bravo 1 prop with one of our 32 or 33 5 blade props.

z.zuperboat

81 or 82 could be possible just by running some good gas and swapping some pullies. I really dont want to do that. My prop slip is over 20% so my best is 74. Its a very controlable ride with lots of slip, the boats not really flying, very level and stable. Im hunting for a prop that will make it feel like a potatoe chip again. In the speedmaster world theirs a big learning curve. Looks like im getting an education in it but havent graduated yet, actually I think I mite fail the corse , LOL The boat had 575 hp went 85 and was fun to drive but a bravo ! Call seatow !!

MOBILEMERCMAN

Z So you added a couple hundred hp's and a few hundred lb's to the boat? Has Jon offered any suggestions? Dave MDG has been working with them. As far props and ratio go My train of thought goes toward working around a 29 inch prop. Reason being since the prop is acting alone, a high pitch like a 35 slaps the at a sharp angle and as they boat leaves and enters the water it side steps the stern alot. Also less pitch will direct your thrust closer to parallel to direction of travel. I know there are many varying opinions and it is expensive to change stuff, But for what its worth here are my 2 cents. I see 5% better slip is 6 mph. It probably wont come easy.
Good luck
Jim

z.zuperboat

John was on the boat this weekend at the race. He looked great lost some weight from his neck inury. Said 94 was fast enough and leave it alone already! I would say most of john experiance is with bravo boats. Dave at MDG runs a conrad using bravo type props, totaly different animal. Ive been working with brett from bblades on props and hes been very insightfull. Also Skip from MRD has been great, its just their has been nothing around to demo ! The only boat around close to my setup is owned by Mr Zul. Everybody has their own opinion and their all different. All agree testing is key. Where can I go to test a bunch of props all at the same time. mercurys lake X ?

MOBILEMERCMAN

Z sounds like your talking with the right people, To some extent John is right. There are some many combinations of heights, ratios and props. Don't get so caught up in they hunt that it stops being fun. The only other guy I know that might offer some insight is Craig Collabella in St cloud he worked at the Lake for years. Again Good luck,
Jim