Question: For all you boat mechanics .. what keeps a boat from planing our or leveling?

(Posted by: on 2010-08-30 07:07:47)

When giving our boat gas to pick up speed it fails to plane out the front of the cabin stays in the air unless we use our passengers to pull it down and then it is ok... we have a 28 ft. boat with a sleep cabin

Posted by: DER ALTE FIRZ on 2010-08-30, 07:17:19

Either you have a propeller that is the wrong size for the engine, or the engine doesn't have enough power to propel the boat at a speed that will allow planing.

Posted by: trunorth on 2010-08-30, 07:27:47

Trim tabs. Engine trim Check em both

Posted by: JetDoc on 2010-08-30, 07:35:30

Sounds like you're loading all the weight (including passengers) too far toward the stern of the boat, but you could also adjust the engine/ outdrive trim for better planing action. Try setting the trim angle down a few more notches.

Posted by: Girly Brains on 2010-08-30, 08:08:21

For a planing hull to get up onto the plane it must leave its stern wave behind and climb up its own bow wave. To get to that point requires a very large boost of power because up until this point the vessel's hull has all the worst design characteristics of a boat intended to go slow. And until this point it's going slow. In direct answer to your question, two things keep a boat from achieving this: 'Suction' and insufficient 'lift'. Moving ballast forward is most certainly a good plan, but from what you say, your vessel seems a bit underpowered. (Or 'overgrown' possibly!) So try lowering the weight of the boat if you can by removing any unnecessary heavy items. (Bilge water for a start!) Crossing your own wash (or that of another vessel, or just natural waves) can help too, as it helps break the suction. And be sure the engine(s) is well adjusted; propeller is of the correct diameter and pitch, and the hull is clean. And remember, the greater the hull's deadrise, the less lift and so the more power is needed to get it out of the water. And a vessel of the type you describe ( "28 ft. boat with a sleep cabin ") will have lots of deadrise. -|--)

Posted by: XTX on 2010-08-30, 09:53:20

If you have an outboard motor the leg of the motor is not at the angle to suck the nose of the boat down to the level plane and allow the boat to skim the water rather it is tail sucking and pushing the boat into the water .... if you have trim tabs they are the same solution as the motor leg ... if you have an I/ O drive then you need to reset the leg and put the anchor and all the gear forward so you have weight in the bow of the boat ... and you need to check that there is no water in the motor well or under the flooring deck of the boat -- because the weight of the water inside the hull is a big factor in the plane and level running of the boat ... if you have water inside the hull then it all rushes to the rear of the boat when you shower-down on the throttle and that weight stops the plane of the boat from happening ............ from / / / longtime old boater .... My question for you is " " what is the hull composition -- wood or fiberglass or metal ?? AND " "what size and horse power is the engine -- OutB or I/ O?? " " " "

Posted by: 45 auto on 2010-08-30, 11:24:47

If the boat used to run good before. Check the bilge and make sure your not CARRYING extra water in the bow and when U power it runs to the stern. Is the bottom clean as just a small amount of grass will reduce the power by 50%. a bent or damaged prop. or incorrect pitch. Engine not running to full RPM.

Posted by: Richard C on 2010-08-31, 13:46:08

It's a weight balance issue, but power can be a big factor. First get rid of most of the stuff you don't need. Make sure that you can get the engines to full power once up and planing. reduce the pitch of the prop when advisable. Then make sure the trim tabs are working and in the bow down position. AND that they are working correctly.

Posted by: Bob K on 2010-08-31, 14:48:55

The boat may have to much weight on it to go onto plane. Check boat placard or paperwork or manufacture for not just number of persons considered safe on board , but also the weights and total weight of everything you put on board or was put on board before you got the boat. Another thought is how the weight is distributed on board. Generally you want boat balanced. Level. Before starting motor. Or read manufactures recommendations. Next is warming motor to operating temp/ performance. And this step goes with first full power than back off to cruise. Set motor to neutral trim at start of trip or on trim setting that enhances acceleration and boat going on step Next could be the way you apply power after leaving dock area. Once on open water advance throttle to go on step, then back off to cruise. Reset trim. And lastly, your chosen cruise setting may be to slow to travel on step. Weight distribution, front to back. Trim setting. If the total weight of the boat is to great for the prop to put boat to plane, or if it takes boat a long time to pick up speed and finally get into plane, then pitch of prop is to great. Buy/ install lower pitch prop to help push weight into plane. On the other side, if boat goes into plane quickly but has no speed, possibly you can go with prop one pitch higher,,? to travel faster while keeping quick speed to plane. Talking with boat/ motor manufacture or experienced mechanic of the boat you have may help you solve this problem. I stake my experience on it. It may take several tries at finding the correct pitch for the cruise, weight of boat and stuff and occupants on board. The last thing is going to be easy to fix or spendy. Head out of port light in total weight. Or install a larger motor if possible on the boat. Or have the motor tuned up. Or use your already found cure.