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gorgar
08-29-2017, 08:59 PM
Hope i'm posting in right place .OK i have an 1969 sweet 16 donzi with a 302 holman moody motor and 270 volvo penta outdrive left hand rotation. Here's my problem it came with a 4 blade solas vb27 10 as written on the prop.When i ran the boat it would only run to 4000 rpms at full throttle. i put on a three blade and the boat was uncontrollable at 45 mph and above i tried to trim out the two stabilizers trim tabs but the boat would sort of porpoise the front end. i talked to the lengendary Ron Hill he said he can make me a prop for it at $600 -$700 but don't want to buy one until i find what is the problem with my boat. Also when i bought the boat the previous owner said he thinks the hull was shaved what ever that means any ideas would be helpful

Just Say N20
08-29-2017, 09:22 PM
What hole is the drive pin in? When you set the drive to use it on the water, the angle is determined by the ⅜"-ish pin that goes from side-to-side in the outdrive.

Is the steering really sloppy? With the boat on the trailer, if you walked back and moved the outdrive (turned it, actually) from side to side, how far can you move it, without making the steering wheel move?

Sola makes a prop called the Titan, that was pretty much designed for a Donzi type hull. It is a 3-blade stainless steel prop. You might want to try a 19", which may be a bit much, but they seem to make the 16 much more controllable than some of the other props. The big elephant ear aluminum Volvo props are not awesome, so stay away from those.

I could not find any documentation telling what a Solas VB27 10 propeller was, so I have no idea what pitch it is. A V8 Volvo 270 has 1.61:1 gears. The engine will go around 1.61 times for the prop shaft to go around once. UNLESS the drive was replaced at some point with a drive from a 6-cylinder or 4-cylinder boat. They had higher ratios so a less powerful engine could still spin their "regular" props (17, 19, 21, 23).

Try and find out what pitch your current prop is.

gorgar
08-29-2017, 10:07 PM
will try pin position it was set at 2nd whole from hull. i will try closer to hull first. The funny thing the boat tracks nice with 4 blade but 3 blade is a wild ride

John C in PA
08-29-2017, 10:18 PM
gorgar, I picked up on this statement you made: " ...the boat was uncontrollable at 45 mph and above...". It sounds like you were experiencing chine walk....and tried to accelerate thru it. Please, don't do that. Because even if the boat starts to ride better, you will have to go thru the rockin' & rollin' again when you decelerate. Very unnerving.

No offense since I don't know how much experience you have behind the wheel. I apologize if I'm wrong.

Oh, and welcome to the board.

John C

mattyboy
08-30-2017, 09:31 AM
what Bill said +1

use the middle hole to test with the first hole closer to the hull may make it bow steer not good the third hole farthest away or up may make the nose to high

a solas titan for the price is a great go to prop go all around pulling, ride , speed , handling think you can find one for under 300 now a days

mattyboy
08-30-2017, 09:39 AM
thinking about shaved they may have taken the built in hook out of the hull if you put a straight edge on the last 3 feet of the chine as it comes to the transom you should see the chine drop down search hook here
and you will see what i mean

if the hull has been modified you may be in uncharted waters and need a benchmark the solas has been proven to be one of if not the best handling prop on a skisporter if a titan misbehaves on I would say it is a hull problem

but again after you have confirmed the steering has no play and the drive doesn't have a nose cone or been shaved too