scary twin engine beast at 50 mph

[31scorpion]

This issue has been making crazy or manybe just crazier. <br />ok twin 2003 225 optis, 31ft center console with a bracket, running 21pitch mirage props, maxed out RPMs are 5400. At 40 she is perfect 4000 rpms, at 50 mph she starts shifting or like a feeling of "skiding" left and right in the back (scary), I thought maybe overproped or engines set too deep(hard to see "x" dimension with a 36" bracket). Anyone have any experiance with twins on a bracket? thanks guys.

 

[Realgun]

Re: scary twin engine beast at 50 mph

Are the engines counter rotating?

 

[31scorpion]

Re: scary twin engine beast at 50 mph

yep yep engines are counter rotating.

 

[Bondo]

Re: scary twin engine beast at 50 mph

That Sounds like you've got a Serious Chine Walk Problem........<br /><br />It Could be any 1 of Many issues that's causing it........<br /><br />We don't see much of that here, but if you mosie on over to hotboats.com's forum for outboard powered boats, I Bet the Guys there can tell you Where,+ How to figure it out........<br />Scream & fly forums are Big Hotrod Outboard Guys too.....

 

[prockvoan]

Re: scary twin engine beast at 50 mph

Have you tryed shifting the load around in the boat?Do you have trim tads?Sounds like you might be triming the motors up to much or they need to be rasied up,rpms are fine.One other thing you can check is,when the boat is on the trailer,get under and check to see if you have any soft spots in the hull,push up on the bottom with your hand.Cupping of the hull will do what you are saying!There is so much that is going on,Have you asked the boat dealer to go for a ride yet?If not,now is the time,could save you some trouble and time.<br /> Make sure you are using a kill switch when boating!

 

[31scorpion]

Re: scary twin engine beast at 50 mph

thanks, i will check for soft spots, i guess i have no choice but to keep raiseing the motors on the bolt holes until they cavitate and then move them back down one hole (i only have one hole left to raise them). Its alot of testing but i guess i shouldn't complain. Jackplates are crazy money, and they would look funny on a bracket. I know this might be crazy but i have 30inch engines (5inch spacer) i wonder if anyone has a 2.5 inch spacer, but then that would mean custom driveshaft, not a good option. It seems i am in the two inch "no mans land" on the height. thanks for your help,

 

[31scorpion]

Re: scary twin engine beast at 50 mph

Oh sorry more facts:<br />No trim tabs, bow lift is fine at low speeds but the boat has very flat angle of attack at low speeds so i thought it didnt need them. #??<br />Boat is old: 1983 so i will check for soft spots.<br />I will try shifting wieght around too. It wieghs about 7,000lbs. mercury reccmends 4 blade props, More "hold" whatever that means. thanks again