Gear,Prop help please!!
 

I just recenty purchased a 24 ft HTM. It has 1.36 gears on a bravo 1 with a 19 pitch prop turning only 4100 rpm at 55 mph..motor is a 7.4 mpI 310hp. i was wondering about going to 1.50 and uping my prop any info would be greatly apperciated!!!

The gear change would help your overall performance from low end to mid range throttle response and not compromise top speed.

Expect to up the pitch on your propeller by 2"s.

i have a 598 ci. in my htm with a 1.36 i run a 28 4 blade if you are looking for a motor mine is for sale 13000.00 let me know and i will tell you all about it

something is not right, the #'s don't work, it come's out with a Positive slip #, thats not possible. check your tach and speedo for accuracy, one of them is not right.

Hello again. i tested a bravo 1 with 1.5 and several different props. it is possible that tach is off but im using gps speedo. I still have a few more to test, so this is mainly an fyi for the experts. we tried a 21p 3 blade and a 23p 4 blade. 21=4900 rpm at 52mph. 23=4200rpm at 56 mph. will try a 22p 3 blade. THANKS!!!!!!

here is a link to a prop calculator, you can input different props and rpms and see the differnece, I still think you need to check your tach,
http://www.rbbi.com/folders/prop/propcalc.htm

23 4 blade slip numbers come to 8.17%. Very good depending on the casting used.

I too have a 1.36 ratio which I believe is easier on the gears and hence life of the drive - answers on a postcard to the usual address - ta

hi i got 24 baja 136 drive 480 hp 21mirage 5200rpms doing 7o mph on gps

1.36 gears can be easier on the drive life. However, if the HP is within the drives capacity, 1.5:1 gears can produce better throttle response and still maintain longevity.

bajabob, your slip is under 8%. That's great for any boat including a Baja!

Brett, Is less than 10% slip actually possible on a straight bottom V-hull?

Possible yes, likely no. Baja's usually run in the11-12% range when they are dialed in. People may say otherwise but ussually there is a missing link in the equation that brings the slip over 10% when you look at it closely. Under 10% is often on a given day with light loads and perfect water.

High slip numbers can mean the best top end speeds on straight V's so, slip isn't always the enemy.

i run my boat in river2riders 50 gallons gas70 mph all the time on gps no bs now builting dart 540 going to dnyo motor shooting for625 hp i no in 2 weeks then i need get new prop hoping to get 80 mph or better got any guest on prop

i run my boat in river2riders 50 gallons gas70 mph all the time on gps no bs now builting dart 540 going to dnyo motor shooting for625 hp i no in 2 weeks then i need get new prop hoping to get 80 mph or better got any guest on prop

bajabob, I believe you have those numbers. Some do! Most don't.

You will need about 2 more inches of pitch depending on the desired rpm levels for WOT.

We have test propellers when you are ready.

Brett

i call in may i will test boati am puting all new parts my motor is set up for 3000 to 5200 for power i no when they dnyo it