Twin outboard mono bouncing problem

[centralrcmystic]

I have built a hurricane with twin outboards. I'm having a bouncing problem. I'm still working on prop angle and the boat is correctly cg'd. Negative prop angle makes it teeter-totter front to back. Positive angle practically lifts the whole boat out of the water. Is prop depth my issue?


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[fweasel]

Can't help you with the ride tuning, sorry, but that is a sweet looking boat.

[HTVboats]

Neat looking setup. Your in a new area as very few twin OB's to get experience. You may want to try some trim tabs. With a single eng nitro OB mono back in the day tabs cured a lot of ills.
Mic

[liteumup69]

I would try to lower the motors a bit, not the angle, but the entire motor straight down. In my bass boat when the jack plate is raised up while driving the boat will start to "hop" until the right amount of throttle/trim is reached. If you start off with the motor all the way up, it takes time to get on plane, and it captivates like crazy

[Fluid]

Normal twin-inboard monos run well with the prop centerline above the hull bottom (in front of the prop). Can't tell the position of the OP's props from the photos. Where is the CG of the boat? At ~43" it should be around 12-13" ahead of the transom, in this configuration it may need to be even further forward. A CG too far to the rear can cause pitch issues, so can prop depth, lower unit angle and prop design.

As stated you are in uncharted waters for such a large hull, it will probably require substantial trial and error....unless you get lucky.



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[centralrcmystic]

Thanks it's going to be trial and error. Just need to be pointed in the right direction. Real boats seem to say raise the prop depth. Cavitation plate should be above water line is what I'm told. Going to try and move the cg a little forward before I start moving the motors

[MarkF]

Also the way you got the props turning is for going strait. Have them spin outwards and the boat will turn better. If the props are too deep there going to try and lift the boat up. Raise the props up a little and see if that helps.

Mark

[boredom.is.me]

Also one other thing. Do you have a reverse flex on the reversed side?

[Hotrods]

Yes he does.

Also one other thing. Do you have a reverse flex on the reversed side?

[Team Lucas]

nice boat. outward props in my experience stops the porpoise affect I think your describing. duel inward pulls the transom down, duel outward lifts the transome

[srislash]

I am with the crew here on prop depth. I have an AC Boats Lazer 40 with twins. Although not O/B's I do run steerable out drives. I did fight with it at first but then realized I mounted the drives too low for the size of props I was aiming to run. So I ended up with 442's and can run most any prop in the 42mm size with a little CG tuning.
I have found inwards works best as outwards flips the backend around in corners.

Having the drives steer creates a whole new experience, you can POWER Thru the corners.

https://youtu.be/6-KjgtRim_Q

[Beaux]

That is a nice looking boat!!

[centralrcmystic]

Got the new heavy duty 7.5 drives on the boat today. Still haven't received the cowls yet soon motors are exposed IMG_5969.jpgIMG_5968.jpgIMG_5965.jpgIMG_5943.jpg

[Keagan-Z06]

Need videos!! That thing is awesome!

[centralrcmystic]

Soon. Prob tomorrow