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Motor speed

Posted: Sun Jul 17, 2011 2:08 pm
by dlandersson
Ok, went out on Lake Michigan today (Sunday) because it was simply too nice not to. Saw another Mac26X(?) on a family outing towing some house monkeys on a nice tube. Spent a fair amount of time just enjoying the weather and getting off on my 5.5" Humminbird GPS screen showing me the depth, the wiseguys bodies floating down from the Chicago river, and where I'd just been. :)

At one point, I raised my swing keel, opened up my water ballast thingy, raised the rudders and maxed out the 50HP Mercury. I went to 9, then 10, then 11, then 12, then 13 and topped out at 14 knots.

I was under the impression Mac26X's will do 20 knots with a 50HP outboard. Am I missing something? Was I impatient? I don't have blue paint like a Mac26M. :wink: so I was expecting a bit more speed.

Re: Motor speed

Posted: Sun Jul 17, 2011 2:55 pm
by Fxwg80hd
If you want to go fast, buy a Blue Hull. If you only want to dream about going fast, then you are fine with a white hull.

Re: Motor speed

Posted: Sun Jul 17, 2011 3:02 pm
by dlandersson
Hmpf... :wink:
Fxwg80hd wrote:If you want to go fast, buy a Blue Hull. If you only want to dream about going fast, then you are fine with a white hull.

Re: Motor speed

Posted: Sun Jul 17, 2011 3:13 pm
by Fxwg80hd
If you really want to go 20 knots (23.015 mph) with a 50hp motor, then I believe you will need to lose the mast, all sails, and every ounce of weight down below. It would also help if you are solo, weight less than 150 pounds, carrying 3 gallons of fuel, and are not going into the wind or against current.

You still might not hit 20 knots, but you should be close.

Another option is to get a bigger motor. I think you will need at least a 70hp to make 20 knots with average load Mac 26X or M.

Re: Motor speed

Posted: Sun Jul 17, 2011 3:44 pm
by dlandersson
Roger...thanks...I feel better. Gonna go start my diet. :)
Fxwg80hd wrote:If you really want to go 20 knots (23.015 mph) with a 50hp motor, then I believe you will need to lose the mast, all sails, and every ounce of weight down below. It would also help if you are solo, weight less than 150 pounds, carrying 3 gallons of fuel, and are not going into the wind or against current.

You still might not hit 20 knots, but you should be close.

Another option is to get a bigger motor. I think you will need at least a 70hp to make 20 knots with average load Mac 26X or M.

Re: Motor speed

Posted: Sun Jul 17, 2011 4:34 pm
by hoaglandr
I tried the same thing on Kentucky Lake last week. Just me with the mast up and the ballast out. Hit 13.7 knots with WOT with my Yamaha 50. Wasn't 20 but still a lot of fun! 8)

With the ballast in I can only hit 10 or 11. :( Some day I'll empty the boat out and leave the mast at home and see what she can do. :D

Russell

Re: Motor speed

Posted: Sun Jul 17, 2011 6:01 pm
by dlandersson
Thank you for sharing - misery loves company. :(

I think I'll try greasing the hull with Pam or something. :)
hoaglandr wrote:I tried the same thing on Kentucky Lake last week. Just me with the mast up and the ballast out. Hit 13.7 knots with WOT with my Yamaha 50. Wasn't 20 but still a lot of fun! 8)

With the ballast in I can only hit 10 or 11. :( Some day I'll empty the boat out and leave the mast at home and see what she can do. :D

Russell

Re: Motor speed

Posted: Sun Jul 17, 2011 6:03 pm
by Y.B.Normal
Russel,

Don't feel bad, most of us can't pull water skiers either. :wink:

About the only Mac 26M owners who are getting 20+ kts have 70 or 90 hp motors on the back.
I have the faster WHITE hull and only get 12.8 kts out of mine (no ballast, 3 on board, the usual overnight equipment/gear, bottom-painted, sails furled). I'm going to try a smaller pitch prop to see if I can get a few more knots out of her.

Lover her for what she is: A roomy sailboat that can outsail any powerboat; a powerboat that can go faster than any sailboat (in calm air). AND we can easily trailer it to another lake when we want a different adventure.

Dale

Re: Motor speed

Posted: Sun Jul 17, 2011 6:10 pm
by Matt19020
I agree with Dale and Fxwg80hd 70 HP full throttle gets me about 16-17 mph fully loaded with ballast and crew and some current....
21 mph running with no ballast and with the current (which I rarely do) also at 6.3 gph fuel usage!

Re: Motor speed

Posted: Sun Jul 17, 2011 7:59 pm
by jschrade
20 can mean a lot of things:

20 mph = 17 knots
20 knots = 23 mph

I can do 17 knots all out on my 26M with no ballast and by myself.

With a skier or tube in the water, that's going to drop real fast. Tubes and kneeboards should work great but skiiing will require a light and good skiier.


Jim :macm:

Re: Motor speed

Posted: Sun Jul 17, 2011 8:39 pm
by Russ
Fxwg80hd wrote:If you really want to go 20 knots (23.015 mph) with a 50hp motor, then I believe you will need to lose the mast, all sails, and every ounce of weight down below. It would also help if you are solo, weight less than 150 pounds, carrying 3 gallons of fuel, and are not going into the wind or against current.

You still might not hit 20 knots, but you should be close.

Another option is to get a bigger motor. I think you will need at least a 70hp to make 20 knots with average load Mac 26X or M.
What he said.

Don't believe the marketing. 50 horses just isn't that much. At 90, you may be hitting that.

Re: Motor speed

Posted: Thu Jul 21, 2011 12:16 pm
by magnetic
I agree; my (white) :macm: has the truly awful Honda BF50 and on a good day can hit about 16.7 knots WOT, plus or minus. That's with the mast and sails on, ballast out, bottom paint, normal kit, just me on board, neutral wind or tide and an arbitrary amount of fuel. At this speed the fuel consumption goes off the chart :x

I also agree with the "just enjoy the sailboat" remark; bearing in mind that most sailing cruisers (in the UK at least) spend easily as much time under power at 6 knots as they do under canvas, and you realise that the Mac really has so much to offer. I get the impression that two full tanks would take me most of the way across the Pacific at 6 knots, and in some comfort down below. There are far worse boats out there to sail in, too, so of you can buy into the "neither fish nor fowl" compromise, I think you're onto a winner whichever way you look at it

Don't buy a boat with a Honda BF50 nailed to it, though. I reckon most electric trolling motors would give you better performance

Re: Motor speed

Posted: Thu Jul 21, 2011 12:50 pm
by DaveC426913
I tried it out last week while singlehanding. Got up to 13.5 knots. That's a *white* hull, fully loaded with gear, in "houseboat" mode, the works. I was pretty pleased.

But omg, I hate trying to steer at this speed. Wallows like a pig.

Still not sure why the hate-on for Honda BF50, but then again, I have nothing to compare it to.

Re: Motor speed

Posted: Thu Jul 21, 2011 1:50 pm
by Divecoz
Did Dear old Rog lie to us?
I doubt it..Did he take every advantage? No Doubt he did.. Did he starve Philippi ( at the helm)for 4 days before the test run? Was absolutely everything as perfect as could be Atmospherically? Had he had his best mold polishers polish that hull? Was his prop a Perfect Match for WOT ? Was the engine running the best it ever could? Would water temp make a difference in drag coefficients? If it does or would it was taken into account..

Does my White :macm: with a 50 HP EFI Mercury swinging a 14 x 10 hit the High Teens stripped down but "carrying" her mast boom and sail? Yes she does..
Did she hit 14 on the GPS pretty loaded down, running for safe harbor, dragging my 9.9 Inflatable and 6 HP and who knows or cared at that moment where the tide was going? But that wind no doubt was pushing me as well. Ye she did ...Could a slim young fellow using my old wooden jumpers , come out on two drop one and for a short distance.... Slalom? Maybe...because a 100 lb kid will have a difficult time getting down for Coming Out of the water.. hahahaha

Re: Motor speed

Posted: Thu Jul 21, 2011 2:39 pm
by WhatKnot
A proper pitch propeller (say that 5 times fast :D ) is key for maximum engine efficiency. Just look up the WOT (wide open throttle) RPM for your make/model engine and compair to what you get wide open with your normal load of gear/people etc. If your RPM are lower, you have too much pitch. If your RPM are higher,you need more pitch.