Repower an X -- With What?

Dimitri-2000X-Tampa · Post by **Dimitri-2000X-Tampa** » Mon Sep 24, 2007 4:56 am

Well Duane, I guess we will continue to disagree on this. I've been around boats a long time and I'm quite sure that the definition of planing is that you are in front of your bow wave (the hump that you see behind you) at which point the boat puts spray out the sides since it is now skimming the water instead of plowing it. And no, if I put a 50HP on my former keelboat, it still would not plane due to the hull design.

Are you sure you aren't making this whole argument up just so you can talk your wife into a larger motor?

LOUIS B HOLUB · Post by **LOUIS B HOLUB** » Mon Sep 24, 2007 8:18 am

Duane Dunn, Allegro wrote:I would never put anything less than a 50 on an X, it is the motor the boat was designed for. You will not gain any sailing advantage with a smaller motor and you give up all the powerboat advantages designed into the boat.

Its nice having that 50 HP power! The Mac is not only a nice sailing sloop, its a nice motor cruizer.

I agree with DUANE, you give up the "powerboat" advantages in this boat with a smaller engine.

tangentair · Post by **tangentair** » Mon Sep 24, 2007 8:55 am

I am with Dimitri on the planning part and my biggest regret is that the Mec 50BF will not fully get my M on step, the nose goes up but if you back off power it comes right back down. If it were on plane, I could back off WOT a little and stay there. I would like the transom beefed up a tad and the recommended power something like 75 to 125. But it might need some chines added for better stability

beene · Post by **beene** » Mon Sep 24, 2007 9:04 am

I have not had any issues with lack of stability.

Very happy with the M's performance that way.

G

Duane Dunn, Allegro · Post by **Duane Dunn, Allegro** » Mon Sep 24, 2007 9:13 am

Tangentair,

Sounds like you are more with me. You describe the exact same thing I do, a 50hp motor does not get a Mac 'On Step' as you say. It does not provide enough power to allow the boat to plane.

I have no problem if people feel the need to describe the behavior of a Mac at speeds below 18 knots as a form of planing. Whatever makes you happy with your boat is fine with me. But until you get 'up on step' and can stay there you are not on a full plane. Planing is more than just leaving your bow wave behind, that is phase 1 on your way there. Phase 2 is not only leaving your bow wave behind but leaving the hole you make in the water behind. You have to do both to be on a full plane. It takes a 70+ hp motor to attain the speeds required to reach a full plane with a Mac.

Then again that's just my opinion based on my 40+ years of boating.

mallardjusted · Post by **mallardjusted** » Mon Sep 24, 2007 9:24 am

It takes a 70+ hp motor to attain the speeds required to reach a full plane with a Mac.

I certainly would repower with a larger than 50 if it comes down to getting a new OB!

Out of curiosity, some have a 60 on their X boats (Frank C?). I wonder if they feel the 60 is enough to get to this "theoretical" plane?

Trouts Dream · Post by **Trouts Dream** » Mon Sep 24, 2007 9:55 am

Although I am new to the Macgregor I had an experience this summer that makes me think that a 50hp gets the boat close to planing. I have a 97X with a 96 Tohatsu 2 stroke. It came with a 12x9 prop. Normally runs at 15 Knots at WOT outfitted for cruising with two or three people aboard. Had one occasion on a glass smooth lake to look down and see we had jumped to 17 Knots as measured by GPS unit and no current. Ran at this speed for about 20 minutes till we arrived at destination. I was unable to reproduce this again all summer. I tried a new prop 12x10.5 but that only made the engine lug and work harder. My conclusion is that once you begin to plane there should be a noticeable increase in speed for a minor increase in throttle as you are no longer plowing water but instead skimming over the surface. I also know that it is not a fine edge between planing and plowing but a transition over speeds. Based on my own experience and numerous posts I have read I would conclude that an X hull has these characteristics.
15 Knots and less plowing
15 to 18 or 19 Knots semi-planing
18 to 19 Knots and above Planing
That being said it will still never be a true powerboat and I sometimes just need to get somewhere fast. If that $%^& Tohatsu would ever die I know I would at least look at more power as an option but still have to consider engine weight while sailing and trailering.
Just my CDN $0.02 worth (Oh yah, same as a US $0.02)

Frank C · Post by **Frank C** » Mon Sep 24, 2007 10:20 am

mallardjusted wrote:
It takes a 70+ hp motor to attain the speeds required to reach a full plane with a Mac.
I certainly would repower with a larger than 50 if it comes down to getting a new OB!

Out of curiosity, some have a 60 on their X boats (Frank C?). I wonder if they feel the 60 is enough to get to this "theoretical" plane?

I think the phrase 'on step' alludes to those powerboat hulls that have a physical step, a beamwise chine crossing the hull bottom, an aft-facing 'step' usually in the after-third of hull surface. On-step means the hull is riding only that aftmost bottom plane. What Duane and others refer to is that those hulls permit one to to throttle-back the engine after the hull has been shoved up, onto the step. Lower RPMs, less noise, greater fuel efficiency, and retrimming the thrust vector ... all are benefits of getting the hull on-step. If Dimitri might be correct about the 26X planing with a 50 hp ... if so, then I'd say the goal is "nirvana-planing."

Mallard, my Suzuki 60 cannot ever be throttled-back, even on early morning, lake-smooth waters, where WOT is 21 or 22 mph. I'd say max for my S-60 wd be 24 mph (perfectly propped). In contrast w/Trout's opinion, I think that magic speed is about 25 mph for my boat ... individual weights & loading will cause slight differences in that speed. While it will change the hull attitude slightly, changing the thrust vector (trimming-out) has no appreciable effect on speed, nor on RPMs. In my opinion, the Suzi 60/70, cannot get the 26X onto a "nirvana plane" or on-the-step.

Do-overs? ... I'd upsize to the new Honda 90 or a Suzuki 140. I've had such perfect and totally trouble-free performance from my S-60, moving to a Honda would be an extremely difficult choice.

beene · Post by **beene** » Mon Sep 24, 2007 11:04 am

Go with the 140 Frank.

Oh, and do give me a call once you have that up and running.

I feel the need, the need for speed.

G

Duane Dunn, Allegro · Post by **Duane Dunn, Allegro** » Mon Sep 24, 2007 6:23 pm

A slightly dated (pre the new Honda BF90) but still an interesting comparison test of 90 hp motors head to head many of which have found their way onto the back of Macs.

http://www.bwbmag.com/output.cfm?id=943183

MacGregorSailors.com

MacGregorSailors.com

Repower an X -- With What?