23cc with twin yamaha f150's, numbers???

[Old'sCool]

What exactly is "wobble"? Those numbers sound pretty good. Are you touching tabs down a bit?

[23acrplanes]

Originally Posted by Old'sCool

What exactly is "wobble"? Those numbers sound pretty good. Are you touching tabs down a bit?

Like the little speed boats get...."Wobble" starts when boat around 6000rpm and starts rocking back and forth gradually getting worse, to the point where I feel like I'm losing control of the boat. Every time I've ran the boat I've had some one with me so I haven't wanted to push it but so hard. I'm taking it back to beach for a few days of fishing so I will be able to get better numbers. I talked to ken with propgods and he told me try to trim thru the wobble, maybe I don't have it trimmed right for the speed.

[Bushwacker]

You're "speed wobble" is commonly referred to as chine walk! Deep V's create more lift as speed increases so the hull lifts higher out of the water at higher speeds, the effective beam becomes narrower, and you lose lateral stability. The chine of a 23 will typically be clear of the water at the transom at about 45 mph. If you lift the hull high enough, it'll tend to bounce back and forth between two sides of the V, so about + 40 degrees on a 20 degree deadrise hull! Had it happen on my boat once in a slight chop with a very light load at almost 50 mph! It's pretty high frequency, quite violent, and can throw you out of the boat if you're not hanging on! If your trim tabs are mounted out at the chines where they should be, lowering the tabs a bit should stop it. I would think it'd be less likely with twins, especially if you're running stern-lifting props like a Merc Mirage, BRP Rebel, or most any 4B prop.

Regarding motor height, the top of the AV plate is intended to be above green water when you're up on plane and fully trimmed out, so have someone else run the boat and look over the transom . . . if you can't easily see the top of the AV plate, the motors need to be raised to minimize lower unit drag. BTW, what's your min planing speed? Most folks don't pay attention to that when testing props, but it's important to be able to hang on plane at low speeds in rough seas. All the original Moesly designs with I/O's or ~300 lb outboards would plane at about 12 mph. The 23 isn't a Moesly design, so it probably can't plane that slow.

[23acrplanes]

Originally Posted by Bushwacker

You're "speed wobble" is commonly referred to as chine walk! Deep V's create more lift as speed increases so the hull lifts higher out of the water at higher speeds, the effective beam becomes narrower, and you lose lateral stability. The chine of a 23 will typically be clear of the water at the transom at about 45 mph. If you lift the hull high enough, it'll tend to bounce back and forth between two sides of the V, so about + 40 degrees on a 20 degree deadrise hull! Had it happen on my boat once in a slight chop with a very light load at almost 50 mph! It's pretty high frequency, quite violent, and can throw you out of the boat if you're not hanging on! If your trim tabs are mounted out at the chines where they should be, lowering the tabs a bit should stop it. I would think it'd be less likely with twins, especially if you're running stern-lifting props like a Merc Mirage, BRP Rebel, or most any 4B prop.

Regarding motor height, the top of the AV plate is intended to be above green water when you're up on plane and fully trimmed out, so have someone else run the boat and look over the transom . . . if you can't easily see the top of the AV plate, the motors need to be raised to minimize lower unit drag. BTW, what's your min planing speed? Most folks don't pay attention to that when testing props, but it's important to be able to hang on plane at low speeds in rough seas. All the original Moesly designs with I/O's or ~300 lb outboards would plane at about 12 mph. The 23 isn't a Moesly design, so it probably can't plane that slow.

Good info! I was scared something was wrong with my boat. Goin to run it now and try some tabs. What props is everyone running with this setup?

[Bigshrimpin]

wow . . . I'm amazed that twin f150's can't turn more than 17p wheels. I'll bet the motors are too deep.

[23acrplanes]

Originally Posted by Bigshrimpin

wow . . . I'm amazed that twin f150's can't turn more than 17p wheels. I'll bet the motors are too deep.

I lowered them 2 holes because it was chine walking too much..... I will probably raise them back up. When I lowered it it def slowed the boat down quite a bit.

[23acrplanes]

Originally Posted by 23acrplanes

I lowered them 2 holes because it was chine walking too much..... I will probably raise them back up. When I lowered it it def slowed the boat down quite a bit.

I saw 47mph today at 6100rpm with tabs in, and a heavy load.