on vipers and props

[pcrussell50]

noob alert...

so far, i feel like most people here on s'n'f, and my prop guy here in ca, who also knows hydrostreams seem to be of a mind that classic hydrostreams, [vipers and vectors], have enough bow lift designed into them that you don't need, [or even neccessarily want], bow lifting props. therefore, by reading between the lines, if the bow is already taken care of, what you want in a prop is a stern lifter, to take care of the aft end of the boat. is this a reasonable line of reasoning?

then again, this guy i know put forth this:

You need to find one of the old Rakers. If you don't have a raker you will have to run trim to lift the bow instead of the prop doing it and that will push the back end down and slow the boat way down. The old rakers had a lot of bow lift which carried the front high with relatively little trim.

this also makes sense to me, and i don't know what to think.

by the way, if rakers and other non-surfacing round ears are bow lifters, what are the design characteristics of stern lifters?

-peter

[Capt.Insane-o]

Eh with a 140 a raker will be fine, especially if you carry a passanger or two. I have a 24 raker at maybe 2 1/2 below the pad (as high as I could possibly go without a LWP) on my Vixen and need to run zero positive trim and it has a great deal of bow lift, perfect for me. I ran a box stock 26 chopper for years on my Viper and it worked great. I run a 24 ET that was worked a tad now because it suits the motor better and a stock 28 ET for running long distances or cruising around. I tried some cleavers and IMO they ****ing suck. Your not going to be seeing speeds with a 140 where too much bow lift is going to be any sort of big deal.

Don't get into too much exactly what people tell you, try a few props and see what you like best. Get some good mounts in the motor and the slack out of the steering and have some fun.

[pcrussell50]

you're right. i've got a toolbox full of sizes to go to: a 19 sst, a 21 sst, a 22 raker, and a 24 raker, for various situations. steering is dual ride guide cable, no idea about mounts, but i bet they are new oem rubbers. i really should get the most out of what i have, and learn about mounts and removing slack, and learning how to drive.

-peter

[Riverman]

My best prop is a 30 Merc cleaver. I gained 4 mph over a 30 chopper.

[transomstand]

I've never understood the concept of "too much bowlift", but I'm not the sharpest pencil in the box. I thought if it was flying too much, you're supposed to push the "down" button:D

I'll give my standard advice. Forget what ya "gotta" have. Try everything you can get your hands on, then decide what you, and the boat likes.

I'm like Capt, I never found a cleaver that ran worth a crap on my boat, but then you get Jeff and Duke of Chippawa who've gotten outstanding results from cleavers:confused:

It's just like that refrigerator light deal, does it really go off when you close the door????

[staylor]

...and as others have posted you do not want to expect that what worked for someone else will work on your rig. In general, most boats in an ideal world will have a prop that pulls best speed with the motor propshaft parallel to the water's surface and the hull running bow up at about a 3-5 degree angle to the water's surface. So each prop you try should have you making a note of the trim gage position at max speed so you can verify the running angle with a little measuring and math afterwards. Or, have someone shoot a pic of the hull at speed and measure from the picture. If you do measurements without a picture, measure the angle between the keel line and the cav plate with the motor set at the trim position where you got max speed- and do this with someone pushing the motor "in" to take out as much play as you can from the mounts. Again- this just gives you a ballpark, since each prop has additional variables that effect speed. When I ran OMCs, the first prop I'd start with was always a Raker, and the second was the SST-RX or SRX chopper. I never ran into a case of having too much bowlift with either of these- but this was with the specific rigs I had.
Doug

[David]

For me, too much bow lift is when the boat never stops moving laterally at high speed. Not out of control chine walk, but not "on a string" either. Since I get this with big ear choppers, which are supposed to have more lift than the average prop, I blame the lift. Could be true.

[thomast87]

staylor is right, you have to play with props, trim, and setback to get the pshaft parallel with the water, bow slightly up, and rpms where you want them. I found that I had too much bowlift with a chopper. Its not all the great to have a lot of neg trim. Some times you can lose w/p by changing the angle of attack, bringing the p/u closer to the transom and slightly more outta the water. Also in my case, cant run the engine as high with the trim neg, it wants to blow out. I assume b/c the cone acts like a wakeboard wanting to skii on the surface due to the upward angle.