We have 2004 Macgregor 26 M with a 50 HP Honda installed. The engine runs fine, however, we are only able to get to a speed of max 8 knots. As soon as we get a speed about 7.5 to 8 knots we get a lot of cavitations around the propeller. As per the Macgregor adds we should be able to get max speeds around 18 to 20 knots. Please provide any feedback we can try to resolve this issue.
Max boat speed with engine
- Thread starter PedSan
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This is only a partial answer since I don't know about the 26M. But, are you attempting to motor at 18-20 kts with the daggerboard and rudder down and the ballast tank full? Any or all of these things could prevent the boat from planing. So could loading passengers and cargo too far forward. I don't know what a normal motoring configuration for the 26m, but I would imagine it involves raising the centerboard and rudder, and probably dumping all or part of the water ballast.
But, it sounds like you are doing something to prevent the boat from planing. This is why it gets up around hull speed, then won't go any faster and the prop cavitates. Find out what's preventing planing and you'll have solved your problem.
But, it sounds like you are doing something to prevent the boat from planing. This is why it gets up around hull speed, then won't go any faster and the prop cavitates. Find out what's preventing planing and you'll have solved your problem.
more details pls
prop size (pitch)? number of blades? ballast empty? Dboard and rudders up?
how much weight? tried shifting weight forward?
and have you owned a power boat before? (familiar w/ how a boat planes).
prop size (pitch)? number of blades? ballast empty? Dboard and rudders up?
how much weight? tried shifting weight forward?
and have you owned a power boat before? (familiar w/ how a boat planes).
Have you watched this video?
It explains what needs to be done to get up on a plane in the first five min.
You may want to watch the entire thing, about an hour.
http://www.macgregor26.com/index/55_min_oct_14_2009.htm
It explains what needs to be done to get up on a plane in the first five min.
You may want to watch the entire thing, about an hour.
http://www.macgregor26.com/index/55_min_oct_14_2009.htm
I have a 26X with a BF50 Honda, and it gets up to about 16 mph or so with 3 men on board (all foils up, no ballast), but otherwise empty (not even cushions - I haven't finished cleaning yet :neutral
. The M supposedly motors better, but I don't know that for fact.
I might suggest you take a picture or two of the stern with the OB full down (or wherever you keep it trimmed when motoring) and the boat sitting still in calm water, and post it so folks who know this boat and engine can see how it's sitting in the water.
. The M supposedly motors better, but I don't know that for fact.I might suggest you take a picture or two of the stern with the OB full down (or wherever you keep it trimmed when motoring) and the boat sitting still in calm water, and post it so folks who know this boat and engine can see how it's sitting in the water.
Thank you for all your sugestions. Let me try to answer some of the questions. I got a new 4 blade propeller
from Honda in the spring. We do follow the guidelines for speed above 6 knots - e.g. Rudders and dagger up. We tried to empty the ballast one day; however, it still did not make a difference.
from Honda in the spring. We do follow the guidelines for speed above 6 knots - e.g. Rudders and dagger up. We tried to empty the ballast one day; however, it still did not make a difference.
The obvious next question would be, what's the diameter and pitch of the new prop? And what is the engine speed topping out at?
the most important thing is engine rpm. you have to start there to diagnose any other problems.your propeller diameter X pitch must let your engine run at 5500-6000 rpm when you are at full throttle.i'm betting this is not the case with your current set-up.
Here are some more details about my configuration. The propeller is a Solas (MYSTH - don't know what that means) diameter: 11,4 and pitch: 10 - this seems like a pretty standard propller for the Honda. The engine is a big foot with the long shaft which also should be the recommandation for the 26 M. It should also be noted that the prvious owner had put bottom paint which may give some friction as it is not as smoth as polished gelcoat.
Last night we took the boat out for some trials.
First run: No change to the configuration including full ballast which provides with WOT 5600 RPMs and 9 mph with a lot of cavitation.
Second run: I removed the transome angle adjusting rod completly (it was in the first hole close to the transome) and trimmed the engine as far down as possible - still full ballast. WOT provided 5600 RPMs and 9 mph - the change was that it removed the cavitations and the engine ran smothly.
Third run: I now removed all the ballast. WOT now provided 5600 RPMs and 17 mph. The boat still had some stern trim, but since the engine could not be trimmed more I told my wife to go in front (120 lbs) moved from stern to front. This configuration provided the RPMs to increase to 6000 - max - it increased the speed to 18 mph. The boat trim is still somewhat to the stern. We did not have more weight to move around so we left it at that.
All in all a succesfull evening. A few questions:
The Honda manual states that you should not remove the transom angle adjusting rod - does anyone have any experience in this respect?
I am not sure if it would provide any change if the propller is changed e.g. Bigger diameter or different pitch - there seems to be a lot thinghs written about this in the past and it is very difficult to come up with any conclusion to what is the best configuration. Any suggestions or experience?
Does anyone actually trim the boat weight wise in order to get even trim when motoring at full speed?
Last night we took the boat out for some trials.
First run: No change to the configuration including full ballast which provides with WOT 5600 RPMs and 9 mph with a lot of cavitation.
Second run: I removed the transome angle adjusting rod completly (it was in the first hole close to the transome) and trimmed the engine as far down as possible - still full ballast. WOT provided 5600 RPMs and 9 mph - the change was that it removed the cavitations and the engine ran smothly.
Third run: I now removed all the ballast. WOT now provided 5600 RPMs and 17 mph. The boat still had some stern trim, but since the engine could not be trimmed more I told my wife to go in front (120 lbs) moved from stern to front. This configuration provided the RPMs to increase to 6000 - max - it increased the speed to 18 mph. The boat trim is still somewhat to the stern. We did not have more weight to move around so we left it at that.
All in all a succesfull evening. A few questions:
The Honda manual states that you should not remove the transom angle adjusting rod - does anyone have any experience in this respect?
I am not sure if it would provide any change if the propller is changed e.g. Bigger diameter or different pitch - there seems to be a lot thinghs written about this in the past and it is very difficult to come up with any conclusion to what is the best configuration. Any suggestions or experience?
Does anyone actually trim the boat weight wise in order to get even trim when motoring at full speed?
I suspect the most important thing here is to make sure you don't!!! get up on plane with your fin in the down configuration. It could be bad when you try to turn. When I say bad I mean very bad, as in the boat could roll violently and throw you and your crew overboard.
Be careful and good luck.
Doug H.
Be careful and good luck.
Doug H.
not an X expert, but with a 50 hp, I think you have the best you can expect.
clearly you need to dump the ballast, and move weight forward to get her on a plane.
you are probably limited on the diameter by the cavitation plate (hitting), but the pitch could be dropped to say 9 (it is a 10 now, right?). but that will mean you need a governor to limit you top RPM to ~5800-6000.
-(cupping the prop edges will also help on the hole shot. *custom prop work)
What I'd suggest is adding a dolphin (planing) plate to the transom. they seem to help with the hole shot, (getting up and on a plane). but do limit the top end speed a bit.
From what I read, the best bet is put a bigger engine, that is not too much heavier than you have now. 70hp seems to be the right power.
again, not an expert on the X model.
I think the metal fins are better, but not really sure...
http://boatingsavings.sportsmansgui...abilizer.aspx?a=623490&pm2d=CSE-BSV-2-BIZRATE
or:
http://boatingsavings.sportsmansgui...le-tail-xl-hydrofoil-stabilizer.aspx?a=623484
lastly: I think the engine mfg like the trim rod to keep the engine from bottoming out the rams. but I've run engines (200+ hp) with no trim rods with no ill effects)... just don't run the trim down too far. (YMMV)
clearly you need to dump the ballast, and move weight forward to get her on a plane.
you are probably limited on the diameter by the cavitation plate (hitting), but the pitch could be dropped to say 9 (it is a 10 now, right?). but that will mean you need a governor to limit you top RPM to ~5800-6000.
-(cupping the prop edges will also help on the hole shot. *custom prop work)
What I'd suggest is adding a dolphin (planing) plate to the transom. they seem to help with the hole shot, (getting up and on a plane). but do limit the top end speed a bit.
From what I read, the best bet is put a bigger engine, that is not too much heavier than you have now. 70hp seems to be the right power.
again, not an expert on the X model.
I think the metal fins are better, but not really sure...
http://boatingsavings.sportsmansgui...abilizer.aspx?a=623490&pm2d=CSE-BSV-2-BIZRATE
or:
http://boatingsavings.sportsmansgui...le-tail-xl-hydrofoil-stabilizer.aspx?a=623484
lastly: I think the engine mfg like the trim rod to keep the engine from bottoming out the rams. but I've run engines (200+ hp) with no trim rods with no ill effects)... just don't run the trim down too far. (YMMV)
I have a 2003 26M with a 50HP Honda and a four blade Solas Alcup prop (11.4 X 10.24) and I am lucky to hit 15 MPH. Back in the days before bottom paint and all the extra stuff I now carry I used to top out at 18 MPH WOT @ 5800 RPM and that was the best I ever got with a nice slick polished white bottom, empty ballast and all fins up with just my wife & I. If you are getting 18MPH count yourself lucky, that is very good.
I doubt you are getting cavitation, it is more likely ventilation, where you find surface air being sucked down to the propeller making it spin faster and over reving. This happens in turns a lot and in choppy seas where hobbyhorsing lifts the stern up and down a lot. You need calmer water to keep the prop submerged. One last small point, a four blade prop has better low speed control and faster mid range speed but top end suffers due to the drag produced by the 4th blade, A three blade prop has faster top end speed (less drag) but lacks the low to mid range capabilities of a four blade. I personally prefer the four blades for the lower end capabilities as I rarely run at WOT. I also have a three blade 10.25 X 13 and that one got me the 18 MPH but I am sure there was extra slippage with the smaller diameter and higher pitch. Still, not bad all things considered.
I doubt you are getting cavitation, it is more likely ventilation, where you find surface air being sucked down to the propeller making it spin faster and over reving. This happens in turns a lot and in choppy seas where hobbyhorsing lifts the stern up and down a lot. You need calmer water to keep the prop submerged. One last small point, a four blade prop has better low speed control and faster mid range speed but top end suffers due to the drag produced by the 4th blade, A three blade prop has faster top end speed (less drag) but lacks the low to mid range capabilities of a four blade. I personally prefer the four blades for the lower end capabilities as I rarely run at WOT. I also have a three blade 10.25 X 13 and that one got me the 18 MPH but I am sure there was extra slippage with the smaller diameter and higher pitch. Still, not bad all things considered.
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