Motor mounting height with 7" setback?

[ebsworj]

I just repowered my boat from 65hp to 90 hp Yamaha today. 18' TideRunner boat, it has a Panther Marine trim tilt system bracket on it that sets the motor back 7". I've heard that the Anti ventilation plate should normally be even with the bottom of the boat. But I read today that since I have a set-back I can mount the motor higher to reduce drag. How far up can I go? I'm not a speed boat by any means but I want the best performance effincey I can get.<br /><br />thanks guys

 

[Chunder06]

Re: Motor mounting height with 7" setback?

I guess this is a dumb question but..does the Yamaha 90hp have its own PTT, if so why do you require a second PTT???

 

[JB]

Re: Motor mounting height with 7" setback?

I would start it 1-1/2"-2" up from the bottom and see what it does, ebsworj. <br /><br />Generally, each 4" of setback calls for a 1" raise, but each boat is different.<br /><br />Good luck.

 

[ebsworj]

Re: Motor mounting height with 7" setback?

Chunder, the anwser is it came that way. The former own had his Suzuki 65hp trim fail and couldn't find a new replacement so he bought the panther trim unit for the warrenty peace of mind.<br /><br />I didn't take the Panther trim/bracket off since it was much easier to add the outboard to than the boat. So now I have two which is weird but useful if I want to use both since the Panther can raise the outboard much futher than the outboard trim if I need to. I'll probably just use the Yamaha trim and 0 out the Panther most of the time.<br /><br />JB - Thanks for the info for 4" set-back raise the motor 1". What effect on performance should I look for if the motor is raise too much?<br /><br />thanks again

 

[JB]

Re: Motor mounting height with 7" setback?

If you bring it up too much you will get prop ventilation. Sort of like losing traction.

 

[Chunder06]

Re: Motor mounting height with 7" setback?

ebsworj, you might start a new trend, with both at full tilt think of the possibilities, inboat prop change, un-fouling the prop, on water foot service. Best of luck with your setup.

 

[ebsworj]

Re: Motor mounting height with 7" setback?

lol, ya even with the old motor's PT not working the Panther system puts it almost horizontal. If its trim up that much and the steering is turned a certain way the steering cable end hits the transom when I lower it, I have to be careful. I haven't tried to use both sytems at the same time yet but It should go past horizontal which would probably be dangerous! :|

 

[deejaycee_2000]

Re: Motor mounting height with 7" setback?

even with the setback, make the anti-cavitation plate level with the bottom of the hull .... I've experiment with this for the last couple of years ... and it just works so much better this way even if you increase the Hp ... the boat on my pic had a 5hp then a 15hp, then a 25hp, then a modified 30hp soon getting a modified 70Hp and I had to change my transom for each engine to make the anti-cavitation plate level with the bottom ... best performance this way ... i promise