Does a Mac 26 Plane with 50HP?

[Dimitri-2000X-Tampa]

Ok, this is a debate that keeps coming up over and over again. Lets see what the opinion of the board members is.

We are assuming that you have the correct prop on there to get full RPM at WOT. We also assume a clean bottom with no boards down.

According to the definition on sailnet: A planing boat skims along the surface of the water like a skipping stone rather than plowing the water aside.

Remember, you only get one chance to vote and you can't change your answer

[Jack O'Brien]

I have had: 7-ft hydroplane with 7.5 HP when I weighed a lot less, 16-ft narrow wood STEPPED-HULL local-made riverboat in Sumatra with 9.9 HP that planed up on the step with two adults aboard, 18-ft runabout with 35 HP, 21-ft Aquasport center console I/O 120 HP Chevy/Mercruiser, 26-ft AnaCapri cruiser with twin 150 HP and it would get up on plane with only one engine, 10-ft 8-in Porta-Bote with 2.5 HP that will plane with one adult.

I think I recognize when a boat planes.

My 2000 X with Suzuki 50 HP, 4-stroke, 6300 rpm, no ballast, no boards, 10.5 x 9 3-blade Suzuki aluminum prop, 18 mph is PLOWING, not planing. Plowing fast for a sailboat but, definitely not planing, IMHO.

I'm sure Billy's XX with the Suzi 140 HP gets up and planes. I would like to think a 70 HP would do it but who really knows? It would be nice to find out, factually, just how much HP it takes to plane empty and how much with ballast and what those speeds are.

[Duane Dunn, Allegro]

Unfortunately I think there is no magic HP that will make the boat plane. Since each of us have our boats loaded differently what may work for one may not work for another.

I would suggest that it's not the HP number that is important, it's the speed attained. If you can touch 20 knots (23 MPH) with whatever motor you have you will most likely find you are on a true plane. A stripped X ala the video can touch this speed with a 50 hp motor. A lightly loaded X with a 70 hp can reach this number. I have been aboard a M with a 70 hp that reached this speed on my handheld GPS with 5 adult males on board. For a boat heavily loaded for cruising with 5 people aboard such as mine, I don't have a prayer with a 50hp. In light day sailing trim we are happy to hit 16 knots pulling inner tubes. In multi day cruising trim we top out at 14 knots. Loaded for an extended trip like our last 23 day one we were happy to get past 12 knots going with the current. (These are all empty ballast speeds over ground on the GPS in Nautical Miles per Hour. Multiply by 1.15 for normal miles per hour.)

To hazard a guess I would think it would take at least a 90 hp to get my cruising load out of the hole and past 20 knots.

[Dimitri-2000X-Tampa]

Yes, well I've owned 4 speedboats (all over 75 HP), 2 large sailboats, 2 small sailboats, a 4HP on an inflatable, and a couple windsurfers. The windsurfer reminds me that there is even a different sound from the water when planing. But you will only have the luxury of hearing that sound on a planing sailboat since the motor on a 26 will overpower that noise. When a boat is "plowing" the water, there isn't much sound from the water at all, when it comes up on a plane, the hissing sound of "skimming" water is quite evident.

Look at this old pic of the 26X, the "plow" is at least 6 inches out of the water.



Water is "spraying" out to the side. If it were not planing, it would be pushing a wave out to the side instead...ie, the bow wave..which is most evident on a craft like a tugboat for example.

Borrowing one of FM's San Juans pics, here is an example of a Mac26 "plowing" through the water and making a wave at the bow.



And finally, regarding "hull speed"...According to this sailnet article, The flat bottom centerboarder and many fin-keeled boats really don't have a hull speed. They are technically "planing", boats.

Planing isn't a function of speed, its a function of weight/length and the shape of the hull, otherwise, you might see a typical destroyer coming up on a plane...not.

If you don't like my definition of planing, then what's yours?

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Edit - I found a new picture of a 26X on a plane since the web.archive.org site seems to be broken.

[marc ducharme]

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Well i am no expert, but i do know that my with a 50hp motor and no ballast looks like Dimitri,s first picture. MY bow is definitly out of the water, even with one person at the bow pulpit. No i dont know if that is what planning is on a Mac, but that is what my boat looks like "planing", all I get is spray comming off the beam. I will post pictures when i get some.

Sailing you gotta love it

[Captain Steve]

Hey, Thanks for the memories! That is my mac...Wildest Dream... "plowing" out under the Deception Pass bridge, towing my dingy.

[Duane Dunn, Allegro]

Fun trip, I've got an even wider shot of all 15 Macs following mine through Deception Pass (silly people, they'll follow anyone) and across Rosario Strait. For your info we were running at 10 knots for that parade on the first day. Not anywhere near a plane or WOT.

I think Billy has said it best

I find the "magic spot" @ about 21+ mph. This is where you can feel the X change attitude, begin to level, and pick up speed. From there on, it just gets better. You know you've left that "hole" behind and now the boat feels like it's sliding over the water with less power. A very slight "chop" seems to produce more speed than slick water. Less wetted surface and trapped air between the hull and surface.

This is when a 26X reaches a full and true plane. At speeds lower than that it is still in the transition phase. You are beginning to climb the wall, the bow has made it out, but the stern is still sitting on the slope not yet up on top. If you want to call this a quasi-plane, perhaps planing on the slope?, I can agree, but it's not yet a full true plane.

With a 50 hp the boat is forever stuck in that half in half out land. It isn't all the way out of the hole.

This incidently is exactly what my dealer told me years ago when I installed fins on the motor and didn't really see any results or added lift. He said because the boat can't quite go fast enough to make it out of the hole, the hydro fins don't gain you the normal benefits of getting to a plane quicker and keeping you there longer at slower speeds. He said all they do is add extra drag. My experience backed this up and I removed them. Maybe with a set of fins the magic speed would drop to the high teens and a smaller oversize motor could do the job.

[Dimitri-2000X-Tampa]

My boat flattens out over its bow wave when it exceeds 10 knots, anything above that is planing. There are differences between a slow plane and a fast plane. What Billy and others who have bigger motors are likely feeling is just a sweet spot on the plane itself. As you go faster, more of the boat raises out, less is in the water which means the center of buoyancy (or center of pressure) moves further back, perhaps riding the best point of the hull. Macgregor may very well have designed these things to handle best at 21-24 mph. That does not negate the fact that the boat is just barely planing at 12 mph.

[Terry]

I can't figure out how to enter my vote, but I vote yes it can plane. Also a quote from http://powerboat.about.com/od/propellers/
"Using a four-blade prop instead of a three-blade prop has several advantages. Your boat will accelerate and come up on plane faster, and stay on plane at lower rpm's. You experience less vibration with a four-blade prop. You will also have an increase in speed at mid-range rpm's, but there will probably be slightly less speed at Wide Open Throttle."

I use a 4 X 11.4 X 9 Solas w/Honda 50hp on my 26M and when I reach top speed (20mph so far) I can feel it getting pretty slippery. I believe that with the right combination of prop-to-engine and perhaps a lighter loaded boat that we really do have the potential to plane. IMHO

[Janusch]

I think technically I'm planning because if you go faster then hull speed (on the Mac 7.5 MPH) you create a suction and given enough suction the boat would sink.

That being said I don't think you plan like a power boat with a 50 hp. In most power boats when you plan you notice a few signs. First the bow lowers and the boat levels off, second you notice a jump in speed with out adding more power, and last your gas mileage for a faster planning speed is higher then the lower speed no planning speed. I have never experanced this in my Mac with a 50 hp. With this horse power I've only been able to get to 20 mph.

God Speed
Dave

[Janusch]

I think technically I'm planning because if you go faster then hull speed (on the Mac 7.5 MPH) you create a suction and given enough suction the boat would sink.

That being said I don't think you plan like a power boat with a 50 hp. In most power boats when you plan you notice a few signs. First the bow lowers and the boat levels off, second you notice a jump in speed with out adding more power, and last your gas mileage for a faster planning speed is higher then the lower speed no planning speed. I have never experanced this in my Mac with a 50 hp. With this horse power I've only been able to get to 20 mph.

God Speed
Dave

[sailpsych]

One way to tell if a boat is planing or not is to put it into a tight turn and see if it slides or not. If it is planing it will slide a bit across the water and turn INTO the turn. It if is not planing it will lean OUT of the turn like an aircraft carrier doing a 30 knot 90 degree turn. This is a result of the angle of the motor to the fulcrum point of leverage trying to turn the boat.

So, YES my Mac26X does indeed plane.

[Dimitri-2000X-Tampa]

Janusch, I don't agree with some of your points:

That being said I don't think you plan like a power boat with a 50 hp.

I agree that the Mac does not plane like a conventional powerboat....but would the Mac act like a conventional power boat with a 200HP on the back? .. I think probably not.

In most power boats when you plan you notice a few signs. First the bow lowers and the boat levels off, second you notice a jump in speed with out adding more power,

I think that both of these things do in fact happen on my Mac...its just that it is much more subtle than "little speedboat with big motor" (versus big hybrid boat with little motor).

and last your gas mileage for a faster planning speed is higher then the lower speed no planning speed.

This could very well be a 2-stroke versus 4-stroke issue. Ie, a 4-stroke will get better mileage going slower than a 2-stroke will. Also, I don't agree that you get your best mileage on the fastest possible plane. On my 3 former speed boats, best mileage was attained on a slow plane...but one still high enough to be in the motor's best torque range. For example, my last jetboat would start planing at 18-20 mph with a top speed of about 55 mph. I got best mileage from 25-35 which was closer to the slowest possible planing speed than the fastest.

[Dimitri-2000X-Tampa]

Seeing as this topic has come back up, I'm going to put this poll back up on top to give anyone who didn't vote the first time, a chance. Please don't vote (or vote "I don't know") if you've never been on a 26X.

Currently, it looks like only 22% of the group thinks that a 26X does NOT plane with a 50HP, the majority thinks that it does.

Edit - sorry, don't mean to say 26X only, can be a 26M also.

[Bobby T.-26X #4767]

Roger Mac would be wise to "up" the HP rating to a 90-115hp. Do whatever's necessary to beef up the transom as needed.
Even offer a retro-fit kit for '96-'02 X's (maybe I can patent that idea).
That way most of us would be much happier and we could put this issue to bed.
It's funny, most of us purchased our X or M under the condition that it will go 20mph+ under power. However, once it's loaded up with gear and people, one needs "more power" to achieve the desired speed. Especially when considering the newer 4 stroke 50hp that is heavier and has less torque than its "2-smoke" predecessors.