planing issues....

J

Jonnytutu

Cadet
Joined
Aug 26, 2013
Messages
8
Hi folks,

so i recently bought a little bombard 8ft rib and have it paired with a 6hp outboard. The question.....i am finding it very difficult get this boat on a plane, it will do it, but it seems very difficult, i basically have to lean over the front of the boat and let go of the outboard (very unsafe practice i know). Should my boat plane easily with a 6hp on there? How about with two people?

looking for any deep thought and insight.....
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: planing issues....

If a small boat is hard to plane driver moving forward is the way to go, try sitting inside floor and extend your arm, much better handling. If with one near strugles to get on plane, much worst with 2- Which brand is that engine ? What's the max rated HP engine stated on transom tech plate ?

Happy Boating
 
J

Jonnytutu

Cadet
Joined
Aug 26, 2013
Messages
8
Re: planing issues....

Hi Searider,

thanks for the reply. The boat is rated for an 8hp, the engine is a 1973 Johnson Seahorse 6hp. I am still messing with the angle of the engine too as I feel its not doing what it should.....
 
deejaycee_2000

deejaycee_2000

Captain
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Mar 28, 2006
Messages
3,447
Re: planing issues....

Put the fuel tank right in the front ... you will have to lean forward .... with 2 people ... mmm probably not ...
 
G

Guest

Guest
Re: planing issues....

Jonnytutu said:
Hi Searider,

thanks for the reply. The boat is rated for an 8hp, the engine is a 1973 Johnson Seahorse 6hp. I am still messing with the angle of the engine too as I feel its not doing what it should.....
Click to expand...
I have sane issue with my zodiac. I am running. 6 merc on it. I lean far forward and tie my anchor to the front which seems to help
 
S

ssobol

Chief Petty Officer
Joined
Sep 3, 2010
Messages
503
Re: planing issues....

weimed said:
I have sane issue with my zodiac. I am running. 6 merc on it. I lean far forward and tie my anchor to the front which seems to help
Click to expand...

If you have marginal power you need to make sure the motor is trimmed in as far a possible to get on the plane without pushing the bow up too much. The faster/higher the bow comes up with power application the harder it is to get over the hump and start planing. Once you are planning you can adjust the angle if you have power trim.

If you can't adjust the engine trim while moving you may need to dynamically adjust the load to get the boat on plane.

I had a 10' rib. With one or two people it got on plane pretty good. With a heavy load it required some people to lean forward for a bit until it got on the plane.
 
J

Jonnytutu

Cadet
Joined
Aug 26, 2013
Messages
8
Re: planing issues....

Thanks for the info folks,

Unfortunately I do not have power trip, i have played with adjusting the trim but when i do it too much the boat starts porpoising when i'm on a plane. I-m getting the motor properly tuned up so maybe that'll help and will continue to mess with the trim.....will try tomorrow. Thanks again for the help....
 
T

tinasdude

Cadet
Joined
Oct 17, 2013
Messages
13
Re: planing issues....

I have a 10 ft bombard with 5 hp 4 stroke. Have the same issue as you. I ordered some lifters from Maxi Marine. They are directly suited for our application. Walmart has a tiller extender for about 29 bucks, I think. My next purchase. Without a larger motor, those 2 things should definitely help mine as well as yours
 
F

fbpooler

Petty Officer 1st Class
Joined
Aug 13, 2011
Messages
334
Re: planing issues....

An 8 ft boat is hard to get on plane. Moving the weight is about the best way to get it over the hump.

You do not have enough horsepower to handle extra drag caused by adding anything to the lower unit.
 
M

mrdrh99

Senior Chief Petty Officer
Joined
Feb 1, 2013
Messages
756
Re: planing issues....

Guys I'm a year or two from upgrading to a decent boat and motor (mariner 4 and trolling motor now). Can someone briefly explain why/how moving weight to the front of the boat helps to put a boat on a plane? Thanks, I'm doing all the research I can now!
 
4

4now04

Seaman
Joined
Sep 25, 2010
Messages
53
Re: planing issues....

A boat that is loaded with most of the weight in the back will have trouble getting the nose to come down when trying to plane. Moving some weight forward will help. Trimming the motor down as far as it will go will also help get on plane.
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: planing issues....

Simple effective rules :

1-Inflate all sib air chambers and keel to a minimum of 3.0 PSI with gauge, reinflateb once on water if needed.-

2-Trim engine to be at 90? brand sticker paralell to water level, usually second/third hole out transom.-

3-Sit on deck, move your weight forawrd as to tiller drive arm confortably, include gas tank too.-

4-Full throttle, if engine has enough power, bow should come down and sib will probably plane with you alone.- Prop must be 100% operational.-

5-If not, you're underpowered, get a 9.8/15 HP, the max rated for or minimum 70% of the max rated for that small sib.-

6-Could add Trim Tabs, Lifters + apply 4 mentioned points.

Note: On a small sib, don't need a tiller extension, your arm is sufficient long to acomplish the work of a extension.-

Happy Boating
 
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E

Elkhornsun

Cadet
Joined
Nov 21, 2012
Messages
21
Re: planing issues....

What I have found to help a great deal was to put the fuel tank at the bow. A 5 gal tank weighs a little over 35 lbs. and it makes a difference. Smaller inflatables will sit down more in the water with any amount of weight than larger ones and so create more drag that the motor has to overcome to get to a speed where the boat will plane.

I had a 15 HP motor on an 8' boat and it did OK but when I put it on a 15' Bombard the motor had a much easier time getting the bigger and heavier boat on a plane. It surprised me until I realized the boat sat a lot higher in the water with its larger tubes better supported my weight and the weight of the outboard.

I have also found that outboards are provided with props that are fine for rigid boats but don't provide enough initial push with an inflatable, especially with dive gear onboard. Changing the prop for one with greater pitch would get the boat on a plane much more readily at the cost of a little bit of top end speed.
 
F

fbpooler

Petty Officer 1st Class
Joined
Aug 13, 2011
Messages
334
Re: planing issues....

The thrust of an outboard motor is below the boat and tends to lift the bow. As you accelerate, pressure from the water tends to provide lift and also restricts movement of the boat. Leverage plays a part so the longer the boat, the less effort to plane. You basically are pushing a boat over a hump, and there is effectively a weight transfer to the rear of the boat until pressures are equalized.

As a reverse situation, think of applying brakes on a moving car. There is a weight transfer which causes the front of the car to be forced downward. The front brakes do a larger part of braking than the rear brakes and wear faster.
 
Sea Rider

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Re: planing issues....

Elkhornsun said:
I have also found that outboards are provided with props that are fine for rigid boats but don't provide enough initial push with an inflatable, especially with dive gear onboard.
Click to expand...

Boating heavily loaded with diving/scuba gear is other story, a same size sib/rib with max rated engine planes near same on flat waters provided that sib is max inflated to, opt trimmed & height seated engine and well ballanced. Factory delivered props works near at top of their stated wot rpm on light loaded sib/ribs as well.

Happy Boating
 
B

blparrish

Recruit
Joined
Aug 16, 2014
Messages
1
I have a Lowe 1650SC fishing boat. My problem is the planing of the boat? When I am alone in the boat and no one up front the boat does plane out ok but the water spray behind me seems to shoot up and comes over the transom some? if I have someone up front I can level the spray out and away from the boat ok? Do I need to adjust motor 40hp or attach some kind of trim accessory?
 
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Sea Rider

Sea Rider

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Joined
Sep 20, 2008
Messages
12,345
Welcome to Iboats,

With engine sitting on transom at 90° you should shim engine with wooden shims untill spray over transom disappears. Must be done under trial and error. Start with 1/2-3/4 inch wooden shims...

Happy Boating
 
C

Chopperbill

Petty Officer 1st Class
Joined
Mar 26, 2014
Messages
389
Going through the same process. Get it going just right and the next time bring a passenger and have to through the whole process again. Now I think I need a different prop to make it do best under all conditions. Conclusion, it's the nature of the beast. Good luck.
 
GA_Boater

GA_Boater

Honorary Moderator Emeritus
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May 24, 2011
Messages
49,038
blparrish said:
I have a Lowe 1650SC fishing boat. My problem is the planing of the boat? When I am alone in the boat and no one up front the boat does plane out ok but the water spray behind me seems to shoot up and comes over the transom some? if I have someone up front I can level the spray out and away from the boat ok? Do I need to adjust motor 40hp or attach some kind of trim accessory?
Click to expand...

Welcome bl. What kind of inflatable boat is a Lowe 1650SC? Please don't post in topics with no activity in excess of 90 days. Start a new topic, I suggest here - http://forums.iboats.com/forum/gene...s/boat-topics-and-questions-not-engine-topics Thanks.
 
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