Do I Need To Repower??

[ChrisP and Pam]

I need some advice. I have a 2005 60hp 4s Yamaha that I bought new in 2005. It's a great motor and I love the darned thing. It starts right up and purrs quietly. But it's not the high thrust version (which is geared lower and swings a 14" prop). I have had 3 props so far. I currently use a 3x12-1/4x9 prop (12-1/4 is as big as I can go or maybe 12-1/2). With 2 people and 24 gallons of gas, 2 batteries and about 40 pounds of anchor and rode, I was able to momentarily reach 18mph (gps) at 5500 rpm which is the spec'd rpm for 60hp. But that's not at all what I expected and it's not planing. And supplied for a short cruise, the top speed drops to about 14-16mph at 5000rpm depending on conditions. At that speed, it is clearly still plowing.

And that would indicate a lower pitch. OK, I get that. So let's say I can find an 8 pitch ( or 7 pitch??) prop and put it on. While that may give me some more weight carrying capacity, I don't think I can carry a moderate cruising load and expect anything more than the 18mph at maybe 5900-6000rpm. Even lightly loaded, what would I get, 18-1/2mph? I'm also afraid that the 8 pitch useful range might be so narrow and that might risk tripping the rev-limiter at the high end and cut into fuel economy at the low end.

Well, as you can see, I'm a little disappointed. I expected my motor to be able to do more than just plowing through the water. So what should I expect? Any feedback will be appreciated.

[NiceAft]

ChrisP and Pam,

May I take a different tack (couldn't resist) on the question at hand.

If you're going to cruise, wouldn't you be more concerned about gas efficiency than how fast you can get there? How much faster do you expect to go?

If your red line is 6000 rpm, then your most efficient speed will be at about 4800 PMs. Your 5000 is close enough. I don't think you will plane under 20mph. I think you would have to get a much higher HP motor to hit the speed you need to plane. Beene has a 70, and he can hit planing speed. I have a 50 HP, Honda 4 stroke, and I can only hit 18 with no ballast.

When MacGregor advertises that their boat can do 22MPH with a 50 HP motor; I would be surprised find out that A) the ballast tank was not empty, B) there was more than one person on board, C) the boat had an anchor, chain, cushions, sails, maybe even the mast. and D) more than three gallons of fuel.

I'm sure there will be someone who can tweak you higher, but you would be using a heck of a lot of fuel for a cruise. On the other hand, if you just want to go fast for the heck of it, well, by all means, push her for what you can get. She is a powersailer


Ray

[ChrisP and Pam]

Ray,
Cruising is the main thing for us. Our 60 is just fine for most things. But it doesn't plane. I'm sure planing uses less gas than plowing. Pam asked me how much faster do I think it should go. And I don't have an answer. But I don't think she would buy a hair dryer that doesn't work on high. Would you buy a roller furler that doesn't unroll all the way out? Why wouldn't I want to use the features that are the allure of this boat? I love sailing but I do like to go fast too. I expect to plane with a normally loaded boat. This is a boat that claims to sleep several people has a galley and a head and should be expected to carry a moderate amount of weight. So the claim that it planes with a 50hp outboard but will only do that when the boat is stripped down to the hull with nothing more than a 160 pound man, a gallon of gas and a just a mainsail is too far from practical reality to satisfy my expectations. But I can deal with it.

So of those of you with a bigger motor who can plane, what brand, model year and hp motor and prop do you use? What kind of speeds do you reasonably expect to get and what kind of cruise load do you carry?

[pokerrick1]

Hey Chris;

This is a difficult subject - - - and I fully understand your point of view - - - especially when you think performance does not compare to advertising. I also like Ray's point of view where fuel economy can be critical when cruising. You are going to be a tough guy to convince, because you've already said you LOVE your engine. WHY, if it doesn't perform?

I personally believe that it comes down to engine make and model. I got lucky and accidently insisted on an engine that I knew almost nothing about, but that has performed admirably for me - - - the Evinrude E-Tec 60HP with the stock prop. If the ocean swells are reasonable, I do plane with a FULL LOAD (including ballast) AND I get good fuel economy - - - I can get 20MPH+ with two people and fully loaded, ie. going to Catalina for a few days @ around 5,000 RPM. My 2S E-Tec outperforms lots of other engines, and it cruises at 4,000 RPM very economically, with little loss of speed - - - maybe 3/4 MPH. In chop I bring the RPM's way down (3,200 and below) to avoid getting soaked, and speed then comes down to 10/12 MPH.

But, assuming you don't have unlimited boat bucks, you are kind of "stuck" (I understand you love it) with your 4S. One of the things you might try is to distribute your load(s) as evenly as possible, but I doubt that accomplishes THAT much - - - but maybe this is a situation where any little help you can get will make a difference to you. Try taking everything OUT of your boat and replacing it with the idea of distributing the weight more evenly. Good Luck

Rick

[Divecoz]

Chris I again agree with a lot of what Rick is saying. I have a 50 Hp Merc. B.F. I swing a 14 x 10(?) prop. I think a Lot of your problem is front load though. Well at least a lot of mine is. That anchor and chain and V berth / storage area?? I got the B.F. for low sped control. The more water you push at low speed the more control you have. There is a point where your 60 is spinning.... may not be cavitating but its Not Biting at what would be considered 100% . Those here who actually get these boats GOING all have Big Outboards 90H.P. and above.
Ricks doing darn well with that E-Tec, btw as I dont think I am quite getting his numbers with my 50 but I am getting very close.
I did see improvement by moving some things aft and leaving the fridge at the dock etc etc. But it was then messy and inconvenient down there at the foot of the ladder and we seldom use the motor for more than a few minutes here and there.
As for what Roger claims??? This is common in all industries. Its called best case scenario / under ideal conditions / and your actual results may vary .....
Look around the dock on your next trip. How many 26 foot ski boats weighing in at or around 5000+ lbs do you see running 50 hp even 100 hp motors? You will see a lot of 150 hp = 300 hp O.B. motors out there though.

[Chip Hindes]

There is no question but that the advertized top speed of the Mac is with one person, empty, no ballast, single battery etcetera. I believe I was able to get very close to it in my new X (50HP Tohatsu 2S) the first time I put it in the water, even with the standard cruising gear, extra battery, etcetera. I say I believe because I was measuring it with a not too well calibrated paddle wheel speedo.

The speeds reported seem pretty close to what everyone else is getting.

It's ridiculous to insist advertized top speed ought to be taken with the boat ballasted, loaded for cruising, several people aboard, etcetera. You don't think 0-60 times in your tow vehicle are done with the whole family aboard and towing the boat, do you?

As long as you are able to make the recommended WOT RPM for your motor with the prop you have, the prop is correct for top speed. Changing props may change the acceleration profile, part throttle performance, cruising speed or gas mileage at lower motor speeds, but it won't change the top speed dramatically; the best you can hope for is one mph or so.

Make, model, 2S or 4S, prop diameter and pitch (as long as you have the nominally correct prop for that motor) doesn't amount to diddly squat when it comes to top speed. It's HP, period. You want to go faster, you need to get a bigger motor.

[ChrisP and Pam]

Exactly! Thank you Chip. Horsepower!

But I am trying to keep it real and I'm not suggesting that anyone blatantly overpower. In fact, I'm on a fact-finding mission. So let's assume a cruise with 2 people for 3-4 days with proper safety equipment and supplies with the weight properly distributed. This is all about the optimal hp motor. So for the moment, let's just ignore the 'factory suggested' hp and the affect of motor weight on sailing performance. The brag is: 22 MILES PER HOUR UNDER POWER WITH A 50 HP OUTBOARD. Well, no one here believes that a 50hp is going to do that job in a practical sense. It just isn't.

So I think the obvious question is who is getting this kind of performance in the real world using the boat in a normal way and with what size motor?

[Divecoz]

E-Tec 60 HP 240 lbs
E-tec 75HP or a 90HP 320 lbs
Got Cash ? grab the 90!
ChrisP, where do you live and what is the dealer offering you $$$$ in trade for the Yamaha?

[Chip Hindes]

So I think the obvious question is who is getting this kind of performance in the real world using the boat in a normal way and with what size motor?

Once you've decided to exceed the factory recommended HP, using the boat in a "normal" way becomes somewhat of a moot point.

If you search the archive, you'll find any number of posts describing boats using 70 to AFAIK the top number of 140.

I've seen Billy's XX with 140HP at speed and I believe his claim of 35mph. I'm sure that's without ballast and can't remember whether it's as loaded for cruising or not, but quite frankly, who cares?

[hvolkhart]

Chris,
If speed is really your thing, why don’t you get your self a light weight dingy and over power this to speed around. Probably cheaper then a 90 hp. You can sail with your sail boat and power cruse with your over-powered dingy

[Divecoz]

IMHO each and every Mac dealer OWES IT to his client / new owner / buyer . . .to strongly suggest the use of a Power Thrust or Big Foot or any other named LARGE Prop Outboard for these boats.
There is absolutely no excuse for selling a New MacGregor with a small prop-ed motor unless the buyer insist on it. Any honest knowledgable dealer should by NOW know how much of a difference the Big Props Make on these boats! Big Props Rule !

[ChrisP and Pam]

No, Chip, normal useage is the relevant point. For this discussion, I would say that the factory recommended horsepower is so conservatively low that it is irrelevant after the warranty is up. The factory has every reason to be overly conservative in their recommendations. In fact, I just got off the phone with Bill at MacGregor and from what has been reported to him, people are powering the boat with larger engines. And no one has reported any hull failures. And as if to prove the conservative nature of their horsepower recommendation, they are still recommending 50hp but when pressed he said that 70hp motors are covered under warranty through certain dealers. And he knows of individual owners putting 120hp motors on them. His concern is for safety of the people if the equipment is handled wrong or excessive weight. I pointed out that variations of a few hundred pounds are well within the normal range of variation. Just inviting someone to go boating can bring in 250 pounds. And that shouldn't be any reason for alarm. So a hundred pounds in the motor shouldn't be a problem either. He said that the weight would probably affect sailing performance somewhat. But he was not concerned about the hull structure. I told him my warranty was up and I was considering a 90hp motor, he said that he personally doesn't have a problem with that and he understands what I would be doing that for. But warned me about safety. He said that this is a high sided boat and it was designed so that it wouldn't be a sharp turning boat. But he gets concerned that someone overpowering a boat and doing 30 knots could trip the boat up in a tight turn.

So the published speed of 22 mph is within safe operating limits of the hull. And a larger hp motor doesn't shock the manufacturer into profuse warnings of hull failure. So a properly balanced crusing load with 2 people could reasonably be considered normal usage. And that is what I call normal usage for this boat. I don't expect much argument there but at the very least, we should all agree that there that there is no wreckless disregard for safety in this scenario.

So who is currently getting the target number of 22mph with a normal load (3-4 day trip with 2 people on board) and what motor are you using

[ChrisP and Pam]

Hvolkart,
Actually, if I tell the whole truth, I have a small boat with a 2006 90hp etec in my sights.
I probably won't get it but that's what's energizing me at the moment.
Chris

[Terry]

Any honest knowledgable dealer should by NOW know how much of a difference the Big Props Make on these boats! Big Props Rule !

The big props simply move more water (larger blade surface) thereby reducing prop slippage and increasing efficiency. Another way around this that I found was going to a four blade prop which also increases blade surface. On the 60HP Yamaha I would bet one could put a 4 X 11.8 X 10 (or 11) Solas Alcup on it to gain some oomph. The 7,8 or 9 pitch does not sound right for 60HP to me. I had my Solas 4 blade re-pitched to 11.4 X 9.75 and it gets me up to 18mph with a Honda 50. The 11.4 diameter provides a bit of clearance to the anti-cavitation plate as the radius is only 6.25 inched to the plate so a 12.25 prop would almost rub the plate. I have read somewhere that there should be about an inch of clearance between the prop blade tip and plate to minimize ventilation problems especially in the turns. One other point about 4 blades is that they do get a boat up on plane faster at lower speeds but ultimate top end is usually 1-2 mph slower. Great for cruising though!
I understand the frustration of not planing as I dislike it too, but for now I cannot justify dumping a perfectly good engine.

[Catigale]

So the published speed of 22 mph is within safe operating limits of the hull.

I dont quite get this. A speed 'rating' is only part of this story of the hull design. By extension, could I double the weight of this boat, install a 200 HP motor and reach 22 mph and claim I am in the safe operating limit of the hull??

Answer: No.