Setting up outboard- jack plate or not?

[Terrierman]

You see more fiberglass trout boats running jets on the White River than you do props.  But I have a 20x48 Shawnee Commissary Boat with a plywood floor in it running a 9.9 Yamaha prop.  Rumor has it the motor has been rejetted to 15 specs but that's just a rumor.  The boat is not lightweight.  But nearly all of the White River boats have a lot of rocker to them and that really helps running shallow. I get where I want to go enough that I ditched the idea of upgrading to a jet.  My boat will run speedwise very close to a 40/20 jet on a boat the same size.  I've also used my boat to float the Eleven Point, James and Beaver Creek.  I can't get up some of the shoals a jet can but other than that they are really close.  A jackplate might make a little difference, but not a lot. 

[JamiePatterson]

Not super familiar with the supremes, but if the boat has rocket built into it I’d run the prop motor. If it is totally flat run the jet. This is based on the 3 river boats I’ve ran over the last 20yrs. 

[JamiePatterson]

Big, sneaky rocks in the middle of the river can cause you trouble with either motor. However, I’ve ran up lots of shallow gravel flats that are just over ankle deep with my 60” bottom Topwater pushed by a 60/40 merc jet -can’t do that with the prop motor.  That being said, I just set up a second boat to run the buffalo. 42”bottom with a bunch of rocker pushed by a 9.8 tohatsu...

[fishinwrench]

1 hour ago, Terrierman said:

Rumor has it the motor has been rejetted to 15 specs but that's just a rumor

It probably is, as many are, but rejetting to 15hp HSjets doesn't make it a 15hp motor.  Gotta swap venturi's and advance timing to increase HP.  

Increasing HSjet size and going to  hotter spark plugs is done to cure the plug fouling on motors run at mid-throttle range alot. It also helps the motor run a little cooler.

[Fishfighter]

It does have a fair amount of rocker. The 207xp is the true flat bottom according to Supreme. I think the tunnel built into my boat was originally intended for prop use. 

[JamiePatterson]

The general rule for setback is every 3” you get away from the boat you can raise the motor 1” vertically -I think lol. It’s been a while...  not sure how that translates on a rig that has as much pronounced rocker as a riverboat.  Anyway, a buddy of mine has a topwater (flat bottom with planning boards) with a 20 Yamaha on a hydraulic jack plate. He likes it, but it kinda seems like one more thing to mess with to me. I’ve jacked around with it and the line between gaining performance and getting to high out of the water is pretty slim. I’d save your money.

Side note: He runs with the motor clamped to the jack plate -not enough room to bolt it down. This led to a pretty scary scenario last year where the motor almost went into the river! He had a death grip on the thing and narrowly avoided fetching it out of the state park hole lol.

[Fishfighter]

Its my understanding that some jack plates are for clamp on only and others allow for bolting on of the outboard.  I wouldn't even consider one that don't allow bolting on.

[fishinwrench]

28 minutes ago, Fishfighter said:

Its my understanding that some jack plates are for clamp on only and others allow for bolting on of the outboard.  I wouldn't even consider one that don't allow bolting on.

If you're talking about an outboard 20hp or smaller it's actually better to attach a chain to the spot meant for attaching a chain on the mount.   I'd rather knock the motor off the transom than to completely bust the gearcase or exhaust housing.

Unless it's a 4-stroke....in which case you're better off insuring it and letting it sink.

[snagged in outlet 3]

10 minutes ago, fishinwrench said:

Unless it's a 4-stroke....in which case you're better off insuring it and letting it sink.

In the 4th year of a 5 year warranty??

[fishinwrench]

40 minutes ago, snagged in outlet 3 said:

In the 4th year of a 5 year warranty??

Whenever.  That warranty ain't worth anything anyway.