side spray

frankgorshin

Cadet
Joined
Dec 28, 2006
Messages
9
I have a G3 165 eagle with a 60 4 stroke yamaha. Its the max hp for the boat. Factory WOT recomendations is between 5000 & 6000. Wide open and trimmed out I get 5600. My problem is I have alot of side spray, starting from in front of the windshield all the way to the stern. My motor is mounted as low as it will go. The trim plate is level or alittle below the bottom of the boat.By raising the motor give me more lift??
 

frankgorshin

Cadet
Joined
Dec 28, 2006
Messages
9
Re: side spray

Thanks I left a few words out of my quote. I mean't will raising the motor give the boat more lift, so 2/3 of the boat isn't in the water on plane??
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: side spray

Adjusting the angle of the motor does that. Theoretically, the antiventilation plate parallel with the bottom of the boat would give the most efficient thrust. But the position of the weight in the boat has to be compensated for. When the operator is in back operating a tiller on the motor, the motor usually needs to be tilted in one hole towards the transom. With the operator forward behind the windshield, the motor needs to be tilted one hole away from the transom. I'm talking about motors with tilt pins instead of power trim.

Power trim allows you to optomize the angle for any given condition. Generally you holeshot with the motor tucked all the way in (DOWN). Once on plane, trim back (UP) to lift the bow and gain speed.

Raising the motor and lowering it on the transom also makes a difference. Theoretically, the best position for the antiventilation plate on the motor is even with the bottom of the hull. Raising the motor up reduces drag which allows for more speed. But it is easy to have the prop suck air in sharp turns and rough water. Lowering the motor down keeps the prop in the water better in sharp turns and rough water, but you'll go a little slower.

Planting the motor further into the water should give you more leverage to get the bow up. Up on the transom would give you less. However the few MPH you go faster with the motor set higher will raise the whole boat higher in the water and the spray will start further back.
Lower is better for pulling skiers. Higher is better for raw speed.

I always advise having two props. One for speed, one for load. You have room for more RPMs, so your second prop should be an inch or two lower in pitch. It never hurts to have a spare if nothing else.

It's all in trial and error and fine tuning for you particular needs. Hopefully these help.
 
D

DJ

Guest
Re: side spray

Planting the motor further into the water should give you more leverage to get the bow up. Up on the transom would give you less.

Theoritically.

Having excess drag (engine mounted low) also works as a lever driving the bow down. Not unlike negative trim-to a degree.

It's worth moving the engine up a notch to see how it effects boat attitude and handling.
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: side spray

I'll bet that boat porpoises with enough trim out to get the best speed. You can usually reduce or eliminate that with trim tabs on the back. I've never had a boat where those haven't helped. The smallest ones would be enough for your boat.

Do you have the regular 60, or might you have a High Thrust 60? That can make a difference too. High thrusts have bigger gearcases and go slower than the regular models.

nv28707_1_400.jpg


nv28707_2_400.jpg
 

frankgorshin

Cadet
Joined
Dec 28, 2006
Messages
9
Re: side spray

No the boat doesn't porpoise. I trim it out until the prop starts to cavitate and then bump it down a notch. The holeshot is great. Just when I'm on plane, the spray comming from the sides of the boat make me think the engine is working harder than it needs to be. The spray is the same at 4000 rpm's or 5600 rpm's
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,274
Re: side spray

Frank, If you have spray off the bow, something may be driving the bow down. You might like to examine the hull to see if it has any hook in it near the stern, or whether someting is hanging below the stern to cause the stern to rise and push the bow down.
 

frankgorshin

Cadet
Joined
Dec 28, 2006
Messages
9
Re: side spray

Chris1956 said:
Frank, If you have spray off the bow, something may be driving the bow down. You might like to examine the hull to see if it has any hook in it near the stern, or whether someting is hanging below the stern to cause the stern to rise and push the bow down.
 

frankgorshin

Cadet
Joined
Dec 28, 2006
Messages
9
Re: side spray

Thanks Chris, just checked under the boat, smooth as a babys but. I raised the motor up 1 hole. Will put it in the water this afternoon and see if that helps.
 

JasonJ

Rear Admiral
Joined
Aug 20, 2001
Messages
4,163
Re: side spray

How is your load distribution? Is there a way you can move some weight back, or do you already have your load optimized?

As far as motor height (X Dimension) goes, there is no hard and fast rule. The height that allows turns at speed and forward motion at speed in moderate to heavy chop without ventilation is where the motor should be. On some boats that means anticav plate is even with the keel, other boats it can be an inch or more above or below. It can be different on two boats that are the same brand with same power if one owner carries a heavy load with multiple passengers and the other always runs a light load and runs solo.

Also, if your max rpm is 6000, then you should be propped to go to 6000 rpms with a light load and just you in the boat. That way if you take a passenger and his gear, you don't bog down as easily.

Looking at the pic that Willy posted, it sounds like you are not that far off of where you should be. It is also possible that your hull design will simply just throw water differently. If there was a way you could have a buddy run a boat next to yours at speed and snap a pic so you could see how it is really running that would be helpful to you.
 

Docknocker

Petty Officer 2nd Class
Joined
Dec 20, 2006
Messages
180
Re: side spray

I had the same problem with my 19ft '63 Dorset / 100hp '63 inline 6 Merc, manual trim. No matter what trim hole I used, I couldn't get her to sit up on her plane pad. Finally figured out that the way the trailer rollers where set up ( about 3" in front of transom ), when she was on the trailer for any length of time, the rollers/motor weight would cause a slight cup in the hull. Solved the problem by putting a piece of 6x6 under the skeg, and running the tongue jack down just enough to take up about 100lbs of motor weight.
You say your hull is as smooth as a "babies butt" but just for the h**l of it, put a good 4ft level on the bottom of the transom with the other end faceing the bow - might be smooth but is it straight?
 
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