socalstone

My 26 outlaw (600sci/xr) has to be trimmed to the moon for best speed.
I don't run it hard often because I know it is stressing the drive and I am asking for trouble.

I'm running a 30 B1 labbed by bblades. It also runs well with a stock 28.
The 30 is a bit tall even after labbing it. (was way too tall stock)
Regardless of what prop is on the boat- seems the only way to get the best numbers is to over trim it.

Are there any tricks that can be done (prop wise) to get top speed without over-trimming? ...take some diameter out? ...more cupping?
or am I just beating a dead horse with a difficult hull?

ps- With the stock XR propshaft looks to be about 6-6.5" below the bottom. No extension box. But I am going to try a 2" IMCO shorty in the next week or so.

MOBILEMERCMAN

sounds like it will like the shorty. If the drive is in the basement you may want to consider raising motor at transom. At present you may still be dragging the fat part of the shorty through the water. Definetely worth trying though if available.

socalstone

Thanks MMM,
I'm looking forward to the shorty, but am thinking top speed may still require excessive trim... true?

Seems to be inherent with non-stepped hulls, and more troublesome with bajas.

MOBILEMERCMAN

If your swinging the whole prop in the water you need to over trim. As you raise the prop shaft less trim is needed and prop selection becomes more important. Ideally you push the boat straight ahead with near neutral trim. With somewhere about a 1/3 of the prop surfacing on your boat. The faster the boat the less gearcase and prop you drag through the water.

bbladesprops

Straight V's like as little hull in the water as possible. That's why the excessive trim makes the boat faster even though the thrust isn't perfectly rearward. As MMM described, direct rearward thrust is the best. However, this gearcase angle doen't always create the bow lift needed in Baja's and the exagerated trim on your hull wins the fight.

If you have the means to test a shorty, do it. We have found they can work on Baja's but enough HP to generate enough speed is a key. Also, planning can become a issue. We can add more tip cup to help depending on the drive height. This can also be a balancing act.

B

socalstone

MMM- thanks for the explanation- that makes sense. I hope the shorty will let me run with less.
I hate the trim angles I've been running- Seems like you can feel harmonic vibrations running through the boat.

B-
The motor is a 600sci. I'm probably going to do a few tweaks from Whipple that bumps the rev limiter and adds about 90hp@5800.
I'll try the shorty 1st. Then, If I don't pull the plug and let 'er sink out of frustration, I'll try the whipple tweak and see where that gets me.
Maybe you can tweak the prop again to maximize the new configuration.

Thanks again.
-Mike

onesickpantera

socal with your propshaft that deep I'm betting a shorty will help. Great explanation MMM!!!

socalstone

I hope so man thanks. I'm frustrated with the performance of this hull so far and am tired of beating the chit out of the drive.

onesickpantera

Have you tried a Mirage+? With your prop that deep I bet a M+ would work well, probably a 29. A M+ carries the bow much better than a Bravo. Every boat is different but I know my Pantera needed a lot less trim to carry the bow with a M+ when compared to a Bravo prop. Even with the shorty a M+ my work well.

socalstone

I have not tried a Mirage. I'd bet a 29 would work well out of the box. I've been thinking a 3 blade might be good (less stern lift) etc. but I was under the impression they only went up to 26 or so. I'm going to look into that. Thanks for the info