Now that I have your attention,,,I finally got my blown strbd motor back in and decided to try my 29" 4 blade Hydromotovives in place of the 3 blade 27"mirages. When rimed to #4 and running 65 it felt very light and unstable in the rear.I had just a slight tab down and I spin out. The boat has never felt that way until I was at 72 with no tabs and #5 on drive trim. Do I need less trim with the Hydros????More tabs????Still got about 10-15 mph but want to still live thru it.Motors are willing,stability is not. HELP!!

some boats don't like the additional stern lift.

My 17' padvee outboard was setup for bowlifting props. One day I tried a 32 Merc Racing Cleaver on it. Talk about clenched rectum. That was absolutely the edge of death for sure. It did run a few mph faster than my labbed 28 Chopper, but it was just nuts. A 32 chopper ran the same 100+ mph speed and was FAR more predictable.

Is it possible that these Hydros need very little trim from the neutral position to achieve the same bow lift(or stern lift like you said)?Certainly feels like stern lift. Seems when I trim from plowing the nose down for planing to what feels like a good cruise trim it's almost instant,maybe 1 or 2 max on the indicators. I thought hydros gave less lift? I didn't mention this is on a 29' non-step Fountain/twin 454 mags. I'll play with it some more today. Any suggestions on tab/drive configuration or should I just sell them and run mirages?

If it makes the boat uncomfortable for you, then ditch them.

I would personally see what they got to offer, both spinning in and out for comparison, before I tossed em. I've not been driving your boat, so I can't comment on how weird it is feeling, but sometimes weird is just different.

mc

if your boat got on plane with the three blades ok then I would most likely keep them on, a lot of the newer fountains have a high X on the drives and you can not get on plane with a three blade prop, for the most stable ride make sure your props are turning out. if you were turning those hydro 4 blades in, swap then around and try turning them out, that will make a more stable ride

try spinnin the props oposite ?

they are spinin' out. I trimed out farther today and it felt better. Got it to 73mph at 4300. More prop than it needs but 54 at 3200 is coooooooooo.Before I was at 73 at 4750 and it takes off just as well. Hope to uprade the other one this winter. When I say it feels wierd (originally)I mean the arse end is moving left and right at speed.

my buddy said 29s are kown for chine walking

What size motors do you have? 4300 rpm's sound kinda on the low side, Jeff

I would try reverse pitching the props to negative 15 degrees and increasing the diameter while decreasing the angle. This will solve your problem and increase your speed by at least 5 mph. Old secret!!!!!!!!!!!!