hydrofoil?

[Hesser]

Another newbe question, sorry but I just don't know. I have a 90hp 2 cycle Johnson with a 3 blade viper prop. Don't know more that that about the prop but since this is my 1st boat, I am not sure about a hydrofoil. I am told that the motor had one and it has been removed. What do they do? I have seen a couple different designs. I would appreciate suggestions.

[Hesser]

Bayhawk, basically a 17' cc flatbottom. I just learned (thanks again Pat) about trimming the motor after launch and yes, it cavitates when I trim and it does do some porposing when running. I see this one at academy and have seen the ones that have the larger plate that runs back and over the prop, whats the difference? I have no problem getting on plane, it jumps right up.

[Rollo]

Are you having any problems taking off getting out of the hole or does the boat nose climb and fall repeatedly without being controlled by your engine trim. if so Roger-Smooth Move has good suggestions; If you dont have any problems you can probably disregard! Also I thought you were gonna let me take your new boat out and thrash test it for you!!I just wanna help the new guy out !! also is that you and your boat on the lower left han corner of your foil............kiddin.

[alex6528]

what do you mean trim the motor after launch? your motor is less likely to cavitate or porpose when trimmed all the way down, if you trim the motor up you will more likely have issues with these. you can get a higher top speed by trimming the motor up, but you are moving the prop higher up and will increse the chance for cavitation or porposing.

[Hesser]

Are you having any problems taking off getting out of the hole or does the boat nose climb and fall repeatedly without being controlled by your engine trim. if so Roger-Smooth Move has good suggestions; If you dont have any problems you can probably disregard! Also I thought you were gonna let me take your new boat out and thrash test it for you!!I just wanna help the new guy out !! also is that you and your boat on the lower left han corner of your foil............kiddin.

Ok so bust on the newbe, got ya. Yes I was going to have you thrash test it but you were not at the dock when we left. No show, no go. 2nd no that is not me but it is my old boat and the guy is the last guy that offered to thrash test it for me, before the accident.

what do you mean trim the motor after launch? your motor is less likely to cavitate or porpose when trimmed all the way down, if you trim the motor up you will more likely have issues with these. you can get a higher top speed by trimming the motor up, but you are moving the prop higher up and will increse the chance for cavitation or porposing.

The first couple times I took the boat out, I did not trim the motor up. I found I could steer to the right with one finger but had to use two hands and only with much effort woud it turn to the left. Pat helped me with the set up of the motor and water tested it for me. He told me that after the motor was trimmed up it turned properly. When I went out Sunday, I played with the trim and it made a world of difference. Turned both left and right with the same effort so I dropped the motor back down and the hard turn to the left came back. When trimming up, the motor gets to a point that is starts to cavitate. I back it down till it runs smooth again and then the bow raises and lowers, what I would call porposing when running slick water. Like i said before, with the motor down, it will launch like mad, then I trim up and its all good.

[tynker]

what kind of boat is it? the foil is to trap water and keep the prop in good water. are you having cavitation problems or is the boat porpoising? might be able to change props.

Not so much to trap water, but to generate lift, to help get on plane faster. It also helps the angle of trim, the more hull out of the water, the faster you go. I have been using the one peice one that is shaped like a wing, can not remember the brand ,but they invented the hydrafoil one piece. Doel-fin invented the concept, it is a 2 piece wing. Both are sold at Academy.