How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

[kippstakes]

Not sure to what tilt angle I should be setting my Ev '72 50hp's engine. Have scoured the internet for tips but am coming up short. I have an old 74 Caravelle v-hull that is sized a lot like this:

http://www.boatmania.com/media/boat...l-runabout-boats-with-windshield-ob-photo.jpg

and tend to go out with only two on board, so pretty light loads- batt. and fuel are in the rear.

Additionally, if anyone knows what angle the trim tab should be set, that would also be helpful.

Thank you

 

[Joe Reeves]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

Engine angle of attack.

View the boat/engine rig from the side while it is on a trailer. The cavitation plate, just above the propeller, should be as parallel as possible with the bottom (keel) of the boat.

 

[jbjennings]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

I'm thinking there should be alignment marks on the trim tab and lower unit. If not, experiment. I'd start by tilting it toward the starboard side about 10 degrees from straight back. If the tab has a curve cast into it, then straight back.
The trim should be set so that the anti-ventilation plate above the prop is parallel to the keel of the boat. If it porpoises at WOT, go down a notch, if it plows, go up a notch.
Hope this helps,
JBJ

 

[kippstakes]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

exactly the two responses i was hoping for.
thanks so much, guys!

 

[emdsapmgr]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

You've gotten some good responses. If the engine is mounted too low, the antiventilation plate will be dragging under water, causing huge water spray at the back of the boat- resulting in loss of fuel economy and speed.

 

[steelespike]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

There are rare exceptions.In the early 60s we had a wonderful 15 ft kit boat with a 18 Evinrude.
It was wide and relatively shallow Front deck was big enough for a great dane dog and it had a center deck and decks either side of the motor.I put the battery and gas rank on the rear seat and I sat on the deck next to the motor.I ran the motor trimmed all the way out
to help raise the front.I was only about 130 lbs. Boat ran great ;the then new speedometer usually made 24-25 mph but in ideal conditions made an indicated 26.

 

[emdsapmgr]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

An ideal trim angle would be the engine set to be perpendicular to the water when the boat is planning. You can also try it by setting the engine back (further outward) one hole. If you go too far back, you'll have trouble getting it on plane.

 

[cgibbo308]

Re: How do I set trim angle on my Evinrude 50hp '72 (specifically, WHAT angle)?

engine trim depends on the way you have the weight in the boat distributed and on water conditions at any given time. depending on the boat and setup, it could even depend on where a passenger moves within the boat. this is why they invented the tilt trim system.

the trim tab on the underside of the cav plate would be trial and error i think. again depends on distribution of weight ( i think)
as it has been said there are markings under the cav p[late to help. i do know there is not much adjustment either way from the zero mark.

i will have to do this once mine is back on the water,, yeah i forgot to take note when i took it off!! Do'H