Planning

[Bay-185]

High guys, new boater and a new member.

Need alot of help. Here is my first question. How do you know you are plaining correctly. I have been reading about trim down and up to get on the right plain. But how do you know you have it right??

thanks

 

[studlymandingo]

Re: Planning

Welcome to iboats!

It would be helpful to know more about your rig; motor size and type, hull size, aluminum or fiberglass, trim type, manual or hydraulic.

Rule of thumb: tuck the motor under as much as possible when accelerating from a stop, as the hull is coming out of the water, you are pushing a wave with the hull, you want to gradually trim the motor up as you get on the wave. Once you are on plane, the speed, your boat, weight distribution, wind, and many other factors determine where you want to be trimmed. I trim out until just before my boat begins to "porpoise"; this tells me that I am at the optimum angle for the speed I am running. It is really a feel thing as it is dependant on so many variables. The best thing is to experiment with your boat, you will feel and hear when you are "in the pocket" once you know your boat really well.​

 

[Bay-185]

Re: Planning

OK, good info I will experiment with that this weekend.

I am running a Bayliner 185 with a 3.0 and Alpha I drive.

On clarification. When you start to porpuise do you trim in just a bit to stop it?

also can you tell if your right by watching the RPMS. i have heard you have got it right if your RPMS drop but your speed stays steady?

 

[studlymandingo]

Re: Planning

Generally when you start to porpoise, it's a little too late; you will have to trim in quite a bit, then gradually trim back out to just before it happens. Have fun experimenting!​

 

[ziggy]

Re: Planning

i'll also add that when trimmed proper, yer rpms for what ever range your operating in will be at it's highest w/o ventalating or porpusing. as you bring the drive down, yer rpms will drop as the bow of the boat gets planted in more water, more friction, less speed, less rpms as the engine needs to work harder. to much trim, and ya may porpise as studly talked about or even ventalate(lose contact with the water and engine races with no benifit)....user yer tach.....

you are pushing a wave with the hull, you want to gradually trim the motor up as you get on the wave

i usually wait till i'm on top of the wave. planeing. then adj trim..... that's just me though......

 

[Bay-185]

Re: Planning

ok so just to make sure I have this right:

1. Trim in all the way.
2. Give it gas and get up to your cruising speed- say 3200 RPMs
3. Trim out and RPMs should go up.
4. Stop before you strart to porpuis.
5. If you go to far bring it back and start all over again.

thanks for the info guys - let me know if I have it wrong??

 

[Texasmark]

Re: Planning

Don't start over. Just tuck it in till it quits porposing or increase speed (if you have it) till it quits.

The idea is to minimize the wetted area. This reduces drag and allows the engine to perform with a lighter load. Hence it will increase rpm's. The idea is to get the max rpm's for any given throttle setting and you have your optimum trim. For slower boat speeds, you can trim out and get porposing. But just prior to that is the optimum speed for that throttle setting.

Now, just for the record, I have a light boat with adequate power. Coming out of the hole I will deliberately trim out forcing the engine to ventilate. It starts screaming, rpm's go to 4k or so and boat speed picks up fast, because I have the rpm's to get the hp outta da engine fast. I go through a transition of getting on plane and then porposing (I change nothing in this process) and then the boat levels out, all with the engine pushed out as far as it will go. My transom has a 20+ inch dead rise so I can't trim out far enough to cause the engine to ventilate at WOT so I can do this. Every boat/engine/setup has it's own capabilities.

But, if you are in heavy seas, you may deliberately want to tuck it in and force the bow down to take advantage of any Vee that the hull has to slice through the waves and give you a smoother ride.....course you want to add power to the engine if you do this to make all this happen. Otherwise you may find yourself with a boat full of water from a wave you took over the bow.

Practice makes perfect. Get to know your boat in all types of circumstances and you will boat happier.

Got it?

Mark

 

[Bay-185]

Re: Planning

Got it!!

Thanks Mark - I will let you know how it worked for me on Monday.

 

[valkyr]

Re: Planning

May I tag a question onto this thread as a new member and prospective first time boat owner?

What is porpoising? I assume its the bow pointed upward out of the water too long instead of pointing across the water?

Prop ventilating? I assume this is the prop breaking the surface of the water?

Prop Trimming? I assume this is prop angle to the boat? Full trim means prop all the way up, or all the way down? What is "Trim out" - prop all the way up, down other?

Sorry to be such a newb

 

[Silvertip]

Re: Planning

Porpoising = bow of the boat bounces up and down at speed.
Prop Ventilating = prop is drawing air and losing its bite. Can happen in sharp turns.
Trimming = the tilting of the engine (outboard) or stern drive (on an I/O) which changes the angle of prop thrust. Actually it tends to raise or lower the bow of the boat. You don't trim the prop -- you trim the engine or the outdrive to which the prop is attached. You trim in for take-off. You trim out on transition to getting on plane and to achieve maximum speed which is the least amount of wetted surface (amount of boat in the water).
Trim In = engine is tilted (trimmed) down = bow down
Trim Up = engine is tilted (trimmed) up = bow up
Tilt = Separate from trim. Tilts the engine or drive up beyond "trim range" for beaching or trailering.

 

[wcsparky05]

Re: Planning

i also have a question for silvertip. what do you call it when your boat leans to port or stern? thx.

 

[Texasmark]

Re: Planning

Maybe Silver missed this.

It's called listing......listing to port (x # of degrees) for example.

Mark