Aquasport 19-1 porpoising in calm water

[Blue Agave]

As far as trim tabs go there is two alternatives and each has it's supporters. Hydraulic trim tabs by Bennett or electric trim tabs by Lenco.

[orb]

Take a few concrete blocks out on the boat with you. Move them around - forward and aft to see if weight distribution could be your problem.

http://www.dlba-inc.com/FAQ7.htm

[lac8362]

I just found these numbers on my prop 13 1/4 X 15 whats a good replacement

[gran398]

lac...the new "WTB aluminum stabilizer" post may be of interest to you. Ck the link to Bob's

[fitz73222]

I just found these numbers on my prop 13 1/4 X 15 whats a good replacement

Do you have a tachometer on the boat? You really can't prop a boat correctly without one. If there is one installed, what are your rpm's at full throttle?

[lac8362]

i do have a tach on the boat advise direction i could take it out tonight or tomorrow morning

[gran398]

i do have a tach on the boat advise direction i could take it out tonight or tomorrow morning

Take her out in the morning, when its calm.

[lac8362]

Ok I got a used prop to try from a local shop 13 1/4 X 17 same diameter plus 2 up on the pitch took out the boat got up to about 23 mph started porpoising also had the engine trim down bracket mount  back one slot so i gained 3 more mph without porpoising Then i tried moving my partner up to the bow sitting on a cooler got up on plane then about 5400 rpm good until put WOT about 6000 started  porpoising real bad had to back off sounds to me like that is a lot of weight up in the bow and i still cant get WOT i am thinking that the motor has to be raised up 2 inches will try to do that this week

[Blue Agave]

Be carful and do not over rev the motor.  Research the top rpm for your year and make of motor.  At best its 5500 - 5800.  Raising the motor will increase your rpms.

[lac8362]

the motor is an 1998  evinrude ocean pro 115  hp

[seabob4]

Me thinks that year OMC wants to see 5400-5600 top bop...

[gts]

I don't think raising the motor will stop the porpoising but it is worth a try since it is a tad low. I have run  a stingray hydrofoil on my 19.6 for 12 years. On many boats they are superior to trim tabs. Tabs push the bow down. With the hydorfoil I could raise the bow without the porpoising which let me run even faster as I was on the sweet spot. this is where the back of the boat is the flatest. Because it is riding on that part of the hull it also has a tendency to eliminate a bit of the uneven loads. I recommend trying the original ones that you have to drill into the anti ventilation plate as it gives the most lift. I did cant the hydorfoil slightly up with an extra washer in the front to get a bit more lift. It did not seem to slow down top end.

Now, after 12 years I had to repower. The new motor is heavier and in order to get the same performance it required canting the hydrofoil even higher. It started popping the heads off the bolt so I put on smart tabs. This stopped the porpoising but I can no longer get the sweet spot. The smart tabs when properly installed do alow the boat to lean into the turns just like it does without them. they are a very good option.

Prior to buying my aquasport I had a roballo that propoised even with shims installed. I mounted the hydrofoils which stopped the problem. The do work very well on some boats.

[lac8362]

Well i raise the motor up to where it should be and i installed a stingray hydrofoil with 2 adults and about 100 lbs of gear motor trimmed all the way forward .the boat  ran WOT 5800 30 mph no porpoising but a little bounce on a 8 inch chop  like it almost wanted to start but didn't thank god now i am returning that used prop 13 1/4 X 17 and am looking for a new one wondering what anyone can recommend thx mike

[gts]

You should call Ken at Propgods. He will tell you what you need. If you are almost propoising with the hydorfoil then you might try the mercruy rev 4 which will give you a bit more lift in the stern. The pitch will be less than with a 3 blade but you will likely be please with the 4 blade. I bought a 3 blade because the four blade just wasn't enough to stop the porpoising so i had to put trim tabs on.