v2racing
Cadet
- Joined
- Dec 15, 2009
- Messages
- 18
I'm brand new here but I have been reading posts here for a little while.
I bought a 1984 Mark Twain Costa Brava 25ft with a single 260 Merc right before the weather here turned cold. I got to take it on the lake one time for about an hour. I could tell right away this boat was not propped correctly. It seems to have a lot of slip and does not get up real well even though the motor seems to be pulling up. It also cruises at too high of an RPM. At WOT it revs to high also. In other words, it doesn't seem to do anything real well. I know it is a large boat for a single engine but it is not what it could be IMHO.
The specs as best I know and can come up with.
25ft 8 ft beam with a very deep hull and the boat is tall.
Weight in NADA is 5200 lbs. I think this may be a little on the light side.
5.7 Alpha 1 260 I/O with the prop pretty deep in the water.
15 1/4" x 15" Michigan Wheel prop in new shape.
Trim tabs.
Will carry 2 people most of the time but may have as many as 8 on rare occasion.
75 gallon fuel tank, large water tank in the bow.
Ran about 3500 RPM to maintain plane with the tabs down at just over 20 MPH.
WOT it would hit 5000 RPM at about 38 MPH.
I don't know how accurate the speedometer or tach are, but if I just went by feel and ear it would back up what they are telling me. I have boated for years and this is just one of many I have had, so I am not new to boating. This boat just doesn't feel right.
I looked at Mercury's prop selector and one of the selections is the Alpha 4 15x16. I am thinking about this prop. I am not to worried about top speed. I want it to plane out as slow of a speed as I can, have good cruising at a reasonable rpm, good handling and maneuvering and good economy. Don't laugh at the last one. Any suggestions.
I bought a 1984 Mark Twain Costa Brava 25ft with a single 260 Merc right before the weather here turned cold. I got to take it on the lake one time for about an hour. I could tell right away this boat was not propped correctly. It seems to have a lot of slip and does not get up real well even though the motor seems to be pulling up. It also cruises at too high of an RPM. At WOT it revs to high also. In other words, it doesn't seem to do anything real well. I know it is a large boat for a single engine but it is not what it could be IMHO.
The specs as best I know and can come up with.
25ft 8 ft beam with a very deep hull and the boat is tall.
Weight in NADA is 5200 lbs. I think this may be a little on the light side.
5.7 Alpha 1 260 I/O with the prop pretty deep in the water.
15 1/4" x 15" Michigan Wheel prop in new shape.
Trim tabs.
Will carry 2 people most of the time but may have as many as 8 on rare occasion.
75 gallon fuel tank, large water tank in the bow.
Ran about 3500 RPM to maintain plane with the tabs down at just over 20 MPH.
WOT it would hit 5000 RPM at about 38 MPH.
I don't know how accurate the speedometer or tach are, but if I just went by feel and ear it would back up what they are telling me. I have boated for years and this is just one of many I have had, so I am not new to boating. This boat just doesn't feel right.
I looked at Mercury's prop selector and one of the selections is the Alpha 4 15x16. I am thinking about this prop. I am not to worried about top speed. I want it to plane out as slow of a speed as I can, have good cruising at a reasonable rpm, good handling and maneuvering and good economy. Don't laugh at the last one. Any suggestions.
