MacGregorSailors.com

Hey Everyone,

As I've gotten more comfortable with my Mac X I've been trying to go further faster. With the throttle seemingly full and RPMs seemingly at full (50hp Mercury going loud but not dangerously loud) it seems like I top out at 8 mph. This is with the ballast tank full, minimal weight, and all of course with all lifting surfaces up (rudders and centerboard).

What are people's findings and suggestions from here? I know this is likely a common topic. Should I open the plug and transom valve and travel for some time to empty it - if so what speeds should I expect when emptied out?

Should I adjust the engine pitch to try planing?

I thought I would ask here first to see how people proceed. Thanks everyone.

-Bob

You need a tachometer to get a reliable rpm reading to diagnose engine and speed issues....noise just isn't a good diagnostic gauge...

Possible issues

Wrong prop
Slipping prop
Cavitation
Engine carb problem
Engine block issues

What year model engine are you using?

Dump the ballast (with boards up of course) and you will see a big speed increase. Full, you are pushing against a lot of water. Get it up on top and it will glide.

Ron

8 MPH seems slow for WOT and full ballast with a 50 HP. You should get about 13-14 MPH (12 kts) at WOT. Check Catigale's suggestions.

Even with a small prop 50 I would agree with the previous post.. Mine is the Big Foot Merc.. I have a 50 HP EFI BF and I consistently beat even the numbers stated below..Please... add additional Information to your avatar at the right >>>>>

rwmiller56 wrote:8 MPH seems slow for WOT and full ballast with a 50 HP. You should get about 13-14 MPH (12 kts) at WOT. Check Catigale's suggestions.

Should be much faster.

You sure the trailer is not still attached?

Lot's of questions - you should certainly be going faster than 8 mph at WOT - unless you are a 26D, D, C etc.

Please update your signature info on the right to include your location.

rpasca02 wrote:Hey Everyone,

As I've gotten more comfortable with my Mac X I've been trying to go further faster. With the throttle seemingly full and RPMs seemingly at full (50hp Mercury going loud but not dangerously loud) it seems like I top out at 8 mph. This is with the ballast tank full, minimal weight, and all of course with all lifting surfaces up (rudders and centerboard).

What are people's findings and suggestions from here? I know this is likely a common topic. Should I open the plug and transom valve and travel for some time to empty it - if so what speeds should I expect when emptied out?

Should I adjust the engine pitch to try planing?

I thought I would ask here first to see how people proceed. Thanks everyone.

-Bob

RussMT wrote:Should be much faster.

You sure the trailer is not still attached?

Genius !

One other option - damaged propeller - spun hub.

Does you speed change between moderate and wide open throttle? If not, the prop could be the issue. Do you have another propeller you can try?

I have an Evinrude 50 on mine and if I just start up and open the throtle all the way, I also get something like 8 knots (GPS.) However, if I let the motor warm up, I get 13 knots with the ballast tank full and 15 with it empty. These speeds are with the board and rudders up. My 'Rude apparently has some electronic protection device that keeps it from going to full throttle unless warmed up, but after a minute of 2 we're up and running. If that does not help, your motor needs service.
Jon

Dreamcatcher wrote:I have an Evinrude 50 on mine and if I just start up and open the throtle all the way, I also get something like 8 knots (GPS.) However, if I let the motor warm up, I get 13 knots with the ballast tank full and 15 with it empty.

Hey, what year MacX and what year engine? (You can list these under your avatar). I have a 98-26X with Johnson 50 of the same age, i am screwing around with props and I am curious.

Regards, P

I have an 2007 model ETEC 50 and I have seen everything from 8 knots, to 16 knots at WOT. I played around with motor trim and found it to makes no difference on this boat with my motor.
Coming back across the bay one time with full ballast in a bit of chop and towing my dinghy, I was maxed out at 8 knots. I rarely go anywhere at WOT but if we are out for a few days, I'll usually blow the cobwebs out of the motor for a few minutes now and again. Mostly I get about 11 to 13 knots WOT with no ballast in (and I'm almost always towing a fibreglass dinghy). I have old bottem paint which they say may rob you of a knot or so..

Before doing anything, you need to try it in all different conditions, as in,, tidal currents, wind, chop etc. First thing you should do is dump your ballast. In powerboat mode, you dont need the ballast and you are really just wasting fuel for nothing.

Ya cant really expect too much out of a 50hp motor. To get the real benifits out of this boat as a planing powerboat, I think you would want at least a 70, or more likely a 90 on it.

BUT - you CAN hand start a 50 hp if necessary.

Mac26Mpaul wrote:I have an 2007 model ETEC 50 and I have seen everything from 8 knots, to 16 knots at WOT. I played around with motor trim and found it to makes no difference on this boat with my motor.
Coming back across the bay one time with full ballast in a bit of chop and towing my dinghy, I was maxed out at 8 knots. I rarely go anywhere at WOT but if we are out for a few days, I'll usually blow the cobwebs out of the motor for a few minutes now and again. Mostly I get about 11 to 13 knots WOT with no ballast in (and I'm almost always towing a fibreglass dinghy). I have old bottem paint which they say may rob you of a knot or so..

Before doing anything, you need to try it in all different conditions, as in,, tidal currents, wind, chop etc. First thing you should do is dump your ballast. In powerboat mode, you dont need the ballast and you are really just wasting fuel for nothing.

Ya cant really expect too much out of a 50hp motor. To get the real benifits out of this boat as a planing powerboat, I think you would want at least a 70, or more likely a 90 on it.

Wow, I am afraid to fiddle with my setup now. I have had my 2000 X / Original 2000 Honda 50 up to a sustained 20.5 kts on the Hudson river. Mast and furler up, no balast, about 55-5700 rpm. My son and I have a combined weight of about 300 lbs. my prop is a 3 blade, assume stock, but never measured.

Maybe I can hand start, but I still think a 90 would be a better motor for this boat If the motor didnt start, I could always sail back, or wait for my panel to charge the battery enough to start the motor, or just call for a tow - In fact, I'm more likely to take one of these options rather than trying to hand start the motor anyway

Personally, I think a 15 or 20hp motor would be more than adequate, but the kids will soon be of an age where they want the thrills of being towed on a tube, and I can't see the 50hp will give them much of a buzz....


John,
Thats amazing, Your not really Roger are you (only his Mac does over 20 knots with a 50 ), or perhaps you were running with 5 knots of current