Basic Theories

[gtsmpuc]

New to this sport I ahve some pretty basic questoins for all you guru's. Setback... how do you know what is enough and how much is too much? Props... what kind of props give bow lift or stern lift? I guess I'm trying to get at what's the difference between round ear, chopper, cleavers and so on?

[patches]

hey buddy welcome aboard. to address your question of setback there are a ton of variables that include type,length,and weight of boat,horsepower,typical load carried.some boats can get by with 0-2 inches some need 16 inches.if you can be a little more specific on your rig i'm certain someone on this board can help you .as for your prop question round ear props such as merc chopper,mazco re3,and srx are considered to be bow lifting props while cleavers are stern lifting props.i don't know near the things that some on this board know but the people on here are great about answering questions so ask away.

[Barney]

The general premise is to get everything you can out of the water to elimnate drag, allow design to fly your boat.
Setback is a lever designed to lift your boat, provide clean water for your prop, a platform to lift your motor out of the water.

In search of the sweet spot! Balance.

Air entrapment hulls have allot of natural bow lift, typically run better with the cleaver, semi cleaver type blades. Round eared props tend to lift the bow, can still function well with all hulls, your hull can be dangerous at higher speeds, 80+, with round eared props.

There are no rules, everything is subject to individual feel, boat, conditions, purpose.

Yamaha Drag/copies are the most popular high performance prop out there, should work great for your hull. Maybe start with cleaver to a Yamaha or similar. Then check on chopper, ET and see what ya think.

[gtsmpuc]

Barney, aren't chopper props, considered round eared, or not? I just got a 26p over the hub chopper jsut to play with. This prop seemed to let the hull actually start to work. I'm still pegging the rev limiter as soon as I get out of the hole. My main problem is my holeshot, I really don't have one. can tucking the motor under (negative trim) hurt my holeshot? I didn't think it could, but I could be wrong?????

[Barney]

Oh those sleepless nights, what to do.......

Negative trim should not hurt your holeshot, although once on plane it may take a few seconds to bring your motor back up and level, negative trim should help you jump out.

I went round and round with props, finnally settling with a large thru-hub exhaust Bravo 1. I still needed to add 20 degrees of negative trim to my setback to make it effective.

Big heavy motor,

Torque,

Exhaust,

I can not really single out any factor. I'm not thrilled with the stock look of the Bravo 1, but it performs really well! I really wanted a 4 blade cleaver, they look sooo cool!

Choppers seem to be a prop that performs well with many different set-ups, they just spin on my boat. With a 2.4 they do just fine, I liked a Yamaha Drag better because of far less cavataion.

I am not a fan of seeing my limiter out of the hole, Ive heard others do it, but that's just my opinion. With the Bravo 1, when I nail it in a negative trim position, the prop will break loose, rpms go to about 3000 and it catches as I leap out of the hole, rpms stay between 3000 and 3500 as she starts pulling up to speed. There is some hesitation as I wait for my trim pump to catch up with my motor position to get me flying.

With the 3.0, I have not found any over hub exhaust props to perform well. Test reports from Hot Boat had Cougars and Daytonas running over 100 with ET's, I have heard several accounts of choppers being the fastest prop too.

The best advice I can offer is this, establish a good relationship with a prop shop, give them a nice deposit and see if they will allow you to test multiple props, try as many as you can.

Props are very expensive, but every boats characteristics are different. I thank Kevin at R&R Props for putting up with my trials.

I believe it was Chad Hill that first recommended a Bravo 1 to me. I see many 300s in Havasu, many. Almost without exception, single engine applications are using Bravos.

Mulitple engines seem to favor cleavers.

If you would like I'll be happy to send you some pictures of my set-up, props and motor position that is working REALLY well for me. It may help you or give you some new ideas.

Email me, I will reply with pictures as I have not figured out how to send pictures over the boards email.