Captain Gecko
Seaman
- Joined
- Aug 30, 2011
- Messages
- 51
Hi,
Not sure if this is the correct forum, apologies if not but I don't now if this is a boat, engine or prop issue.
My 24' cuddy runs perfectly. 5.7 merc 260 alpha one. Engine starts and runs smoothly. Cruising speed I see around 25 knots at about 3800 rpm. Pushing to 4000 rpm I see about 28-30 knots.
Once I start pushing to WOT (4200 rpm plus) I get a recurring issue. The engine will rev high and the boat loses speed. It's like the prop is losing traction. Ventilation? Not sure. I have to cut the throttle, wait for it to 'grab' traction again and then it's fine.
What I have found is the deeper I have the engine trimmed, the earlier the issue occurs. If I trim all the way down, it occurs very early, far before WOT. If I trim higher, the issue holds off until higher RPM. If I trim even higher (probably about mid-way through my range), I can pretty much go WOT. However, the instant I trim down a little bit at WOT, the issue hits. Very predictable, I can re-create it every time.
The trim tabs also seem to affect the issue. With the trim tabs all the way up, it occurs earlier. With the tabs down, it helps reduce the issue.
The problem is, if I keep the engine trimmed to the position where the issue does not occur and I can hit WOT, the boat porpoises heavily. So I'm obviously trimmed too high at this point.
Other than this, the boat runs very well.
Ideas?? TIA!
Not sure if this is the correct forum, apologies if not but I don't now if this is a boat, engine or prop issue.
My 24' cuddy runs perfectly. 5.7 merc 260 alpha one. Engine starts and runs smoothly. Cruising speed I see around 25 knots at about 3800 rpm. Pushing to 4000 rpm I see about 28-30 knots.
Once I start pushing to WOT (4200 rpm plus) I get a recurring issue. The engine will rev high and the boat loses speed. It's like the prop is losing traction. Ventilation? Not sure. I have to cut the throttle, wait for it to 'grab' traction again and then it's fine.
What I have found is the deeper I have the engine trimmed, the earlier the issue occurs. If I trim all the way down, it occurs very early, far before WOT. If I trim higher, the issue holds off until higher RPM. If I trim even higher (probably about mid-way through my range), I can pretty much go WOT. However, the instant I trim down a little bit at WOT, the issue hits. Very predictable, I can re-create it every time.
The trim tabs also seem to affect the issue. With the trim tabs all the way up, it occurs earlier. With the tabs down, it helps reduce the issue.
The problem is, if I keep the engine trimmed to the position where the issue does not occur and I can hit WOT, the boat porpoises heavily. So I'm obviously trimmed too high at this point.
Other than this, the boat runs very well.
Ideas?? TIA!