Motor change with a lot of options

[DaveB]

Thats True! sometimes you want to switch your GPS to MPH to get that feeling you are going faster. But if you are doing dead reconing it's always best to use Knots.
I always use Knots but if I have a guest on board and they want to know how fast we are going I give them MPH and thats not over ground.
Dave

I assume those who are getting up to 28 are measuring in Statute miles per hour. All the speeds I refer to are Nautical miles per hour, the only unit of measurement that should be used on a boat as all distances on marine charts are in Nautical Miles. 25 Nmph = 28.75 Smph.

[vkmaynard]

... the only unit of measurement that should be used on a boat as all distances on marine charts are in Nautical Miles.

No we like Statute miles like in our car and experimental airplane. Numerous aircraft finally use Statute miles in measuring distance and speed. Carry two GPSs if you are worried about one failing requiring you to dead recon.

Beware of Solas bad prop database. The new prop does not fit our boat like they said. Our friend with his M/Etech 90 is going to try the 13.25x13 4 blade tomorrow. It fits his motor. He currently maxes out at 25 mph lightly loaded.

I can't imagine someone could make 31 mph on 75 hp. Billy is only getting 36 mph on a 140 hp Suzuki (real world, I was on his boat seeing that speed). It sounds like the statements made on this board claiming that boats are "planning" on a Honda 50. Not going to happen.

Trying to find another prop tomorrow.

Victor

[Duane Dunn, Allegro]

Some here have argued that any speed beyond hull speed is planing, but I beg to differ. In my opinion planing is when the boat fully climbs out of the hole and the bow drops, this is a full plane. On an X this happens around 18 knots. My 50 could not reach 18 knots, nor could any boat with a 50 I've ever heard of. It all depends on what your definition of planing is.

[beene]

Hi guys

John is referring to mph, just for clarification.

On another note, that was just after we installed the Merc 75, and my hull was virgin new, very lightly loaded, 1st full season, 2 adults and 2 kids o/b water was at 800 asl and cold/smooth w/ light ripples, perrrrrrrrrrrrrrrrfect for a speed test.

I have personally water skied behind my M with a 14x11. Normally I run with the 14x13, as in the speed test.

I was 195lbs when I last water skied behind my M, and the boat was heavily loaded with 1 adult and 4 kids + my fat but dragging behind LOL.

As for measure of speed, it does not matter to me, I live in the world of aviation, so I am used to constantly switching from SM to NM and back.

To make things worse, I live in Canada, so everything else is in metric Kph.

Still, just like the video and brochure for the Mac, everyone I talk to, when asking me about boat top speed with the motor wot, are speaking in mph.

Like I said, to each there own. Makes no difference to me.

Also, now, few seasons later, hull not clean anymore, scratches, chips, bottom paint, more stuff o/b then ever before, I now get 24.5 mph wot ballast empty.

Can't seem to break that anymore.

I still cruise at 19 mph 3/4 throttle, so at least that is still keeping me happy. I use the large 1600cc to get her up on plane, then back off.
I have found with that practice, I can roll the thttl back to 16.5mph and she still holds a nice plane. Any slower and she sits back in the water again and the spray/speed/handling etc all falls off.

Cheers

G

[Kelly Hanson East]

Chapmans Guide states that statute miles are preferred inland and nautical miles coastal and offshore

I'm sure there are other sources that might disagree but chapmans is certainly a reputable reference source

[beene]

True

All of my Navionics charts for my gps use sm also.

NM seems to be more for oceanic activity on the water.

The great lakes charts are all in SM

G

[DaveB]

Duane,
When I first bought my MacX 2 years ago it was empty and with 420 lbs persons and two 6 gal fuel with the 3 blade prop it got to 15.3 knots on my 50hp 11yr old Honda.
This speed was on a semi plane. This means I was out of the hole and bow almost down.
To get it on full plane would require 16-17 knots in calm waters.
Thats wide open and burning fuel at a much more rapid rate than a 90 HP at 2/3 speed doing same Knots.
If one wants to Cruise at Planeing speeds it only makes sence to get a high torque 75-90 hp engine for lower fuel consumpcion.
On the other hand if you want to Cruise at 6 knots and seldom want 14 knots than the 50hp is fine but it should be with a high thrust Motor with larger Prop.
Dave

Some here have argued that any speed beyond hull speed is planing, but I beg to differ. In my opinion planing is when the boat fully climbs out of the hole and the bow drops, this is a full plane. On an X this happens around 18 knots. My 50 could not reach 18 knots, nor could any boat with a 50 I've ever heard of. It all depends on what your definition of planing is.