About 6.2 kts on our Mk1 M25 seems to be about it. 3 blade fixed prop.
But that's at wide open throttle (about 3200 on our tach, which we have not calibrated), which we don't usually do except for brief spells, we've learned that it doesn't add much speed but burns A LOT more fuel. Running at 2800 we do about 6.0 kts.

[QUOTE=benethridge;10855]

I upped the potentiometer as far as it would go, but it still isn't registering the correct RPM (as shown by the laser tach). So I'll replace the tach one of these days. [/QUOTE]

Before replacing your tach; is the alternator stock or aftermarket? The tach needs to be set for the number of poles in the alternator. I'm not sure what the stock tachs are, but I replaced mine with an Ample Power alternator; it has 14 poles, which is not the same as the stock unit on the M35A (maybe 8?). The number of poles is set with dip switches or a rotary dial, depending on the model tach. If it doesn't match that, the tach will be way off, more than can be corrected with the potentiometer. When I replaced my alternator, the tach read WAY high.

I believe the tach manual is in the Technical section of this website, but couldn't locate it with a quick search. I downloaded it, so it much be somewhere.

With my bottom down to gelcoat sand and smooth, just barrier coat and ablative paint on boat she will turn 7- 7.3 knts with zero tide. I have a 3 blade sailorcampbell prop

OOOOPS I forgot she is a MKI C36 TM fin keel and has a M-25 in her :cool:

[QUOTE=jsc4484;10870]With my bottom down to gelcoat sand and smooth, just barrier coat and ablative paint on boat she will turn 7- 7.3 knts with zero tide. I have a 3 blade sailorcampbell prop[/QUOTE]
Hmm... looks like you'd blow the doors off us in a "drag" race. I wonder what the secrets of your speed are, given that we have the same engine and hull configurations. I had always attributed our not being able to get up to hull speed (we definitely can go faster under sail) to the limitations of having only 21hp in the M25 (and assumed that was why later C36s had larger engines, such as the M35.)
Not that I'm usually in a hurry to get anywhere...

I truly dony know, the speed which I stated she was turning around 2300 - 2400, but I friend of mine has the same boat and I walk by him like he is standing still, when we head out to the race committee boat.

I do agree on not rushing, I think the only I'm in a rush is if the BEER has run out. Now that would be a TRAGEDY :eek:

I suppose you guys need to answer some questions up front, in order to make sure you're comparing apples to apples:

1) Are your tachs calibrated?
2) Are your knotmeters calibrated?
3) Are your hulls freshly cleaned?
4) Are you both in salt water or both in fresh water? (buoyancy would be different)
5) Are you both in No Wind conditions?
6) Are you both in the same sea state?

Unless the above can be determined without doubt, there is no value in comparing such info.

I'm working off GPS speeds as well, and similar hull and sea conditions (including current).
Only difference (outside of the 2 vs 3 blade fixed props) is that I'm in salt water. I'm assuming that since its more boyant, we would be faster, no?

Oh, well, given that Ben's boat is on a lake 1,000 miles away, I won't have to race against him for that beer!