Trim and planing for a 14' aluminum

[sierra 18]

Hi all:

I've been out a few times now in my new (to me) 14' Lowe fishing boat, 35 HP Johnson with power trim. First time out, I was suprised how high the bow rides at lower speeds (of about 5 knots). I tried adjusting the trim up and down (my console does not have a trim guage) in small increments. The adjsutments made no difference at low speed, even with the weight as well-distributed as possible.

As I get closer to the 15 knot speed, the power trim seems to have more effect, and once I'm at about half of full speed, I can just touch the trim to put the motor up a tad, then a few seconds later the bow just drops and the boat seems to slingshot forward. Top speed is about 24 knots.

A friend of mine who has more boating experience than I tells me that the bow will just ride high at the lower speeds, and it will only plane out with the trim adustments once you reach the mid range, and faster, of the top speed that your boat will do. Is this the case? If so, I'll just get used to peering around the bow when coming into the harbour.

Thanks all,

Chris

 

[RL Gman]

Re: Trim and planing for a 14' aluminum

Trim all the way down until plane.

Once on plane, very small adjustments up to bring some of the boat out of the water for faster WOT speed.

Trimming the engine up should not drop the bow period. The only time that would happen is if you just havent gotten over the bow wave to plane. However, in that senerio, the trim should still be all the way down.

At slower speeds, trim wont do anything, except create less draft, and poorer steering.

Try small adjustments on trim when your on plane to get the feel of it.

 

[RL Gman]

Re: Trim and planing for a 14' aluminum

PS. The trim guage is pointless. Better for you to learn without one if you ask me. Better to get the "feel" of the boat than use that pointless gauge...

 

[sierra 18]

Re: Trim and planing for a 14' aluminum

At slower speeds, trim wont do anything, except create less draft, and poorer steering.

This confirms what my friend had told me, that at slow speeds, the trim won't make much difference.

Thanks for the quick reply, much appreciated.

 

[RL Gman]

Re: Trim and planing for a 14' aluminum

Thanks for the quick reply, much appreciated.

No problem at all! And BTW, welcome to the forums and congrats on getting that boat. I started on something very similiar...I've gone bigger since, but I think my best times were on my little flats boats...

 

[sierra 18]

Re: Trim and planing for a 14' aluminum

Certainly is manageable when you're one person trying to launch and later, recover the boat back on the trailer.

Great forum, very helpful members here.

C

 

[lncoop]

Re: Trim and planing for a 14' aluminum

After I bought my first pontoon I was without a flatbottom for the first time in 20 years. I COULDN'T STAND IT! My wife got tired of my moping and told to me to go get another fishing boat already. Love the family party barge, but I'm lost without a flatbottom in the back yard. Enjoy the Lowe and welcome to an outstanding forum.

 

[Boatist]

Re: Trim and planing for a 14' aluminum

Welcome to the board.
It might help if you understand what happends as you gain speed in the water.
To start with your ideling along and the boat is level in the water. At this speed the boats is affected just by the weight and it placement in the boat.

As you begin to speed up the boat will start to push water ahead of the boat.
At this speed have very little thrust out of the motor so trimming up or down will also have very little affect.

At about 7 miles per hour most boats the bow will start to clime up on that bow wave you are pushing so the bow starts to rise.

At about 10 to 14 miles per hour the bow will clime all the way up on top of that bow wave and the bow will be very high. Motor trim will still have very little affect.

Every boat is different but about 16 to 18 mph most aluminum boats will clime up and over that bow wave.
When you go over the bow wave the bow will drop back down on the water and you will gain a lot more speed with very little change is throttle.
This is called planing. Also at this point motor will be putting out a lot of thrust so triming the motor up or down will raise or lower the stern of the boat.
When the stern riases the bow lowers and vice versa.

Also you can watch the spray coming off the hull.
As you start it will be up off the bow but as you gain speed the spray will move further back on the boat. With a netural trim when you reach planing speed the spray will be coming off the boat form midship and more toward the stern.

At planing speed you motor thrust will have a big effect on boat trim.

Best way to get going is idel out past your 5 mph zone then make sure everyone is seated.
Trim the motor in for bow down and go full throttle.
This means the motor is going to have full thrust and raise the stern and help keep the bow lower.
As the boat reaches planning speed you can reduce the throttle or trim the motor for the ride you want.
This will will get you on plane fast and acutal save fuel.
You will not be climing that bow wave for a long time and the bow will not rise as high.

 

[ENSIGN]

Re: Trim and planing for a 14' aluminum

All you need is a fat girl friend to sit up front

 

[sierra 18]

Re: Trim and planing for a 14' aluminum

Welcome to the board.
It might help if you understand what happends as you gain speed in the water.
To start with your ideling along and the boat is level in the water. At this speed the boats is affected just by the weight and it placement in the boat.

As you begin to speed up the boat will start to push water ahead of the boat.
At this speed have very little thrust out of the motor so trimming up or down will also have very little affect.

At about 7 miles per hour most boats the bow will start to clime up on that bow wave you are pushing so the bow starts to rise.

At about 10 to 14 miles per hour the bow will clime all the way up on top of that bow wave and the bow will be very high. Motor trim will still have very little affect.

Every boat is different but about 16 to 18 mph most aluminum boats will clime up and over that bow wave.
When you go over the bow wave the bow will drop back down on the water and you will gain a lot more speed with very little change is throttle.
This is called planing. Also at this point motor will be putting out a lot of thrust so triming the motor up or down will raise or lower the stern of the boat.
When the stern riases the bow lowers and vice versa.

Also you can watch the spray coming off the hull.
As you start it will be up off the bow but as you gain speed the spray will move further back on the boat. With a netural trim when you reach planing speed the spray will be coming off the boat form midship and more toward the stern.

At planing speed you motor thrust will have a big effect on boat trim.

Best way to get going is idel out past your 5 mph zone then make sure everyone is seated.
Trim the motor in for bow down and go full throttle.
This means the motor is going to have full thrust and raise the stern and help keep the bow lower.
As the boat reaches planning speed you can reduce the throttle or trim the motor for the ride you want.
This will will get you on plane fast and acutal save fuel.
You will not be climing that bow wave for a long time and the bow will not rise as high.

Very useful info, thanks. I don't have a lot of experience so I have to rely uponthe advice of those who do. I never knew I was pushing a bow wave, but it makes sense now.

 

[Captain Caveman]

Re: Trim and planing for a 14' aluminum

Your motor is probably least efficient when you are riding up on that bow wave (i.e. pushing water). Most people will say that you either putter along without pushing water or get quickly onto plane and then adjust your speed. I'm not a big fan of going full throttle just to get on plane, but you don't want to be sitting on that bow wave either. If you are pushing water / riding the bow wave then you are 1) asking your motor to do a lot of work for minimal results, and 2) limiting your forward vision depending on how high your bow rides before dropping down on plane.

Give it anywhere between 1/2 and full throttle depending on your desire. If you get on plane in 2 to 5 seconds you should be fine. If it's taking longer then you need to give it more juice.

A 35hp motor on a 14 foot boat ought to produce some good speed. Enjoy!

 

[dockwrecker]

Re: Trim and planing for a 14' aluminum

All you need is a fat girl friend to sit up front

Or two skinny ones.