Getting On Plane

[888MFG]

I have been using an 11.3 bass boat with an 8 hp engine for quite a while. I just purchased a used Sport Craft 20 Foot CC.
The engine is mounted on a Stainless Marine outboard engine bracket. The engine about 18 inches back of the transom.
As using a a large outboard (140 hp) is new to me, I am unsure of how to adjust the engine angle for the best performance. According to what I read the engine should be in the most down position to bring the bow down. However with the engine back from the transom does this still apply? I have been very cautious about going faster than a slow troll until I am more sure of the way the boat will react. Thank you for answers in advance.

 

[garbageguy]

Sounds like you got a nice boat, get 3 posts in and put up some pics (or it doesn't exist).

Briefly, put the outboard all the way down to start (after it's in the water that is deep enough), give it some good throttle to start going up on plane (hole shot), and trim up once you start feeling it getting up on plane - then you'll likely want to back off on throttle a bit . You'll get a feel for how the boat reacts and how much throttle/trim to give it and when. Go with a friend who is familiar with this to learn, if you can. As long as your boat is set up and running/maintained properly, I don't think you'll hurt it. It's a machine, make it work for you.

 

[Scott Danforth]

do you have a jack plate in addition to tilt and trim, or just tilt and trim?

similar to garbageguy with just tilt and trim....trim down, mash throttle, as the boat comes out of the hole, I simultaneously back off throttle while trimming up until nose starts to porpoise, then trim down just a tad

with a jack plate, things get a bit more complicated as you can also raise the motor.

 

[888MFG]

No jack plate. I will try your method this weekend and let you know how it pans out. I am reluctant to mash throttle on such an old engine but will start down and trim up as I go.

 

[ziggy]

reluctant to mash throttle on such an old engine

ya don't have to mash it assuming your not under powered. with my old engine i roll on the throttle, not just stab it down. i don't even hit wot to get on plane. you'll feel the boat come out of the water as it come up on plane. after yer on plane ya can back the throttle off to where ya want it. after yer at the speed ya want on plane, then ya can trim out/up. as ya trim out/up, engine rpms will increase as less of the boat is in the water. speed will also increase. ya can back off the throttle some more to bring speed back down to where ya want it.
there is a point of no return though. at some point you'll start to fall off plane, bow will rise as boat starts to plow again. you'll have to find this spot for your boat. for me, it's at about 2100 rpm. at 2k rpm for me, i start to fall off plane. trim back in/down to maintain plane at the lower rpm range of plane.
also as stated above though. if ya start to porpoise, yer trimmed out to much, so bring it back in/down if ya start to porpoise. down to highest rpm w/o porpoise.
as for the set back engine. i can't comment. i'm certain it will have effect, but the idea of getting on plane should be the same.
fwiw, if ya wanna go fast quickly. ya can trim out/up just after yer on plane while yer still adding throttle or even at full throttle. as ya get to know yer boat, you'll find out how much out/up trim ya can get away with w/o adverse effects. like porpoise.
proper trim will be at highest rpm for whatever speed your going.

 

[5150abf]

Just gas it and play with it, that is the only way to learn how it will react, you are not going to hurt anything.

A stated generally you start out with the engine trimmed down close to all the way, hit the gas and start trimming up in small increments, you will hit a point at or near top speed where the engine will blow out, prop starts sucking air or the boat will porpoise, the front move up and down as if you are going over waves when there are none, in both cases trim down and bit until either condition stops and you are there.

Time running the boat and trying different trims at different speeds is the only way you will learn what your boat wants, as I said , you can't hurt anything so really no worries now get out there and start playing.

Oh and I believe the name for the mounting plate is a GIL bracket, it allows you to run the engine higher on the boat than if it were mounted directly to the transom getting the engine farther out of the water and giving you a higher top speed..

 

[dingbat]

Generally speaking, thrust should be directed parallel to the plane of travel.

Hull dynamics and prop will dictate what works best for your particular hull and engine combination.

Knowing that my bow rises coming out of the hole, I compensate for that negative rotation by using a positive trim angle (verse all the way down) coming out of the hole to minimize bow rise. From there is just a matter of mashing the throttle(s) to jump up on plane.

Once on plane, I adjust the trim angle so that the top of my motor is parallel to the water. From there I adjust the tabs to compensate for any lean then tweak the trim until I loose all feed back of prop torque at the helm.

At this point I can walk away from the helm and the boat steers it’s self.


Running a bracketed boat is no different. If anything you’ll need a little less trim coming out of the hole due to the boyancy the bracket adds to the stern

 

[888MFG]

Here is a picture. Thank you for all the info