bsullivan403

A few months ago i purchased a 2004 Avance 26 CC. came with twin 25" merc 250 efis. I had trouble getting the boat to plane off. after countless hours we determined the motors were set too low and water was covering the exhaust relief ports when planing off causing the motors to bog down. When there was weight in the boat if the weight was up front it would plane off, move the weight to the back and it wouldnt plane. it has 23' mirage plus props. the boat weighs 4950lbs with motors. The boat would cavitate some and i had no bow control with the trim and the motors were set to the lowest hole. So we concludeed the boat was built for 30" motors. I convereted the motors to 30" and raised the motors up 3" which put the lower unit 2" deeper into the water. Now I have great control of the bow but still have a problem planing off. Even when i am by myself I have to hit the throttles and walk to the front of the boat until it starts to plane then rush back to back down on the throttle (i know, not safe. lets save the flaming and stick to the point). My mechanic has gone through both engines completely and says they are perfect. He believes this is a design problem with the boat and even the weight of the fuel is causing me problems. I cant find any information on these boats let alone someone else that owns one. Im at a loss as to what to do next. Does any one have any ideas on these boats or the set up? Thanks in advance.

turbo rr

I am a little confused with your post. You said that you had 25" motors that were too low.....But then you converted them to 30"? Have you tried a pair of 21" props? Do you have trim tabs on your boat? Are the engines on the transom or on a bracket? Need a little more info.

bsullivan403

The upper portion of the motor was too low and water would wash up the cowling and cover the exhaust ports. The lower unit wasn't deep enough in the water. They are on a bracket and I do have trim tabs. I've tried to use the tabs and it still won't plane off without shifting weight to the front of the boat. I have not dropped prop size yet. I would've thought a 4900lb boat with 500hp could spin 23"s easily. I've been trying to get my hands on a set of 21s to try out just to see.