change thrust angle?

flyin brian

Cadet
Joined
Mar 19, 2006
Messages
9
The bow of my boat raises tooo much. Would like to know how to change thrust line of engine to keep the bow down. It is at its' limit of down thrust now. But it won't go to parelell (sic) with the transom. Any ideas??
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,453
.It would help if we knew the HP of the motor and type of boat. Usually OB motors have a tilt pin that limits the minimum trim. That pin (if you have one) should be lowered until the situation improves.
 

flyin brian

Cadet
Joined
Mar 19, 2006
Messages
9
I have 15 hp Evinrude on a 12' aluminum V bottom boat. I can overcome some of the lifting by adding weight to the bow but would rather change the thrust line. I have it set to the maximum down thrust now, but it isn't enough. Any way to increase it?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
You should be trimmed at a hole that achieves engine sitting perpendicular to engine and combo riding parallel to water level with weight evenly distributed on deck. Usually second-third hole out transom.

01-Correct Trim Angle.JPG

Place a boating mate up front, go full throttle, check if handles, planes better. Other issue could be engine is not siiting at the sweet engine/transom height ? Do you have out, over transom water splashes at speed or prop aereation at close turns when on plane ? You could be under propped if running underpowered OB's for that size boat ?

2-Ballance & Trim.JPG

Without knowing HP and boat type won't be of much help...

Happy Boating
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
You have the motor set with the prop as close as possible to the transom?
Your 15 with you alone should reach speeds around 20 to 25 mph.
If it is under powered the bow is likely to be unusually high.
Most boats have a transom with a slight outward angle as pictured in the illustration.
There are a few odd ones with almost no angle.You can buy or make wedges to go between the motor mount and the transom.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
How is the condition of the bottom of your boat? Any hook or rocker? If you sight along the bottom from the transom forward, the bottom should be STRAIGHT. If it bulges outwards (rocker) or is pushed inwards (hook), that might be the cause of your issue and no amount of motor angle or ballast is likely to fix it.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
I have seen them but I don't know who makes them: There are wedge blocks that fit under the transom clamps and will change the angle of the engine. Especially useful if the engine is at the limit of its tuck-in and you need more down thrust at the transom.

You can also make your own trim tabs out of .080 aluminum and rivet them to the transom. Adjust to the angle needed to bring down the bow and add a brace or two.

OR--buy Smart Tabs.
 
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