85 18ft Hydrasport with a 99 Xr6 150, Am I doing it wrong?

[King6]

Hello All, Im new to the forums, not new to the boat.

I have a 1985 Hydrasport Bass Boat,owned it for 3yrs now. I dont remember the exact model..something like V240-480 or something of the like. It has the kevlar lined hull. Its been a great boat that I had powered by a 1973 Mercury 1150 up untill about a week ago when the lower unit went out on it and I decided it was time to jump on a newer motor that was priced right. This old 73 Merc 115 was bolted right to the transom and handled quite well. I noticed on the boat transmom there was holes from a jack plate on the boat from a previous owner (who knows how many people owned it before me and how many engines have been on it.) When I installed this new motor with the jack plate , I drilled the holes an inch lower because thats what the boat it came off of was measure at. (2000 basstream)

Details on the boat layout, small livewell in front (empty) larger livewell behind seats (empty but with no plug in so maybe a gal or 2 of water) 2 Deep cycle trolling batters in the rear, 2 starting batterys infront of the steering console, 10 gal of gas in the tank located at the stern and generally pretty light for gear.

I now have a 1999 Mercury Xr6 150hp on it, attached to a 6" Manual Jack plate, The jack plate in its lowest adjusted position, and the motor bolted 3/4 up on the jack plate. After days of searching I come to a conclusion that a 23 pitch prop was best suited for this application, but then it was recommened to get the Solas Scorpion SS prop and to go one pitch size larger, not being sure I ordered 2 props, one standard solas 23 pitch, and one Scorpion SS 24pitch.

I tried the scorpion first, with the trim down as much as possible, I tried giving it throttle and the nose of the boat is shooting straight up..more so then I ever seen before and feeling very uncomfortable, the water at the transom was dangerously close to coming over so I didnt punch it to WOT to see if it could get out of the hole. (especially since I had my son with and didnt know what kinda mess I could be getting in) I tried this several times with various trim angles but never throttleing it to WOT because it was just to sketchy, it seemed like the boat wanted to do back flip.

I then put on the Solas 23 pitch, and this time results were less sketchy like, trimed all the way down, the bow still would go up really high and the transom getting close to the water line but I felt more comfortable to throttle it out of the hole and get it to plane. Once on plane Its smooth sailing untill you hit any wakes or chop and It starts jumping them instead of cutting into them. Witch my 73 Merc I could trim down and bust/cut through chop or wakes, trim up and glide on the water.. This setup seems like im always gliding on water and when I come off of plane, the wake wash's over the transom.

Is my motor to low? to high? Am I to heavy in the stern now with a larger motor? Am I just using the wrong prop?

Everyone says to measure the jack plate differently, witch is the correct way? with the center of the boat level, and the engine level, I measured from the floor to the center of the prop shaft 11 3/4" and from the bottom of the boat to the floor 17-3/4"





Motor mounted height on the jack plate:



I made a video with the Solas 23pitch, The cavitaton plate is still under water, Im reading it should be above water, but then I also read it should be level with the keel . I was told to lower the motor more to get it to plane faster.. but it looks like the motor already sits really low in the water. Any lower and im going have water washing over the hood when I throttle down.

[swamprat]

Is that a 25" motor,how is the prop shaft height in relation to the bottom of the boat

[RCollins]

Your prop shaft centerline is way too low at 6 inches, should be in the 3-3 1/2 inch range, measured from the very bottom of the boats pad, not the bottom of the setback step. These boats do sit low to the water at the transom and water coming over the back when you stop is going to happen. Most people just give it a little gas for a second to get ahead of the backwash when stopping. A hole shot plate across the bottom of the jack plate should also help in that regard, to keep water from running up under the jack plate when you stop. You won't eleminate it all together. Keep an eye on water pressure as you raise the motor, but at 3 inches or so, you shouldn't have a problem.

The only thing I see in the video is the cowling just about goes under water on the hole shot, raising the motor will reduce that. The cavitation plate should just be out of the water when under way. Putting a whale tail on it will help keep the nose down on the hole shot, but will be out of the water also when on plane .

[swamprat]

I might be wrong,but looking at the pics.this motor is jacked up pretty high in relation to the transom.Im just thinking he has a long shaft motor and is going to have a hard time getting the propshaft at the right height in relation to bottom the boat

[lilmule]

To deep,and to low a pitch prop,unless sking a 23 would pull 2 up,while a 24 p is right for most boats my vl270 uses a 25m yamaha,for 2 up and gear full ivewells,and a 27 for one up and speed.Hydrofoil will help getting on plane does look long for a 20 in,3 1/2 under 25P trophy+ or equivilent

[MWT37]

Motor is way to low 3.5 prop to pad then up from there if its a 25" shaft you may not ever get that high try raising the motor and a 4 blade 24p trophy

[MWT37]

Is that a aluminum prop? If it is get rid of it and go stainless way to much flex in aluminum for that motor

[90 5.0]

It might be just the picture but that sure as heck looks like a 25" shaft motor.

If so you have too options, buy a 20" mid section for a 2.5(that's what an xr6 is) you can normally find one for 400 or so with trim ram.

Or sell the whole thing and buy a 20" XR-6

did XR-6's even come in 25" shafts??? I though they called the salt water series or something but not xr6 nomenclature then??

anyways I it's a 25" it's gonna give you fits forever.

Also ditch the aluminum props, buy a used 24-25p trophy or a yammi 25 t1 to start with.

[lilmule]

I have an 83 vl 270,while rated for a 150 its a light boat,above 60 was a handful,much better ride in chop with an old 140 it ran 59 mph,also ran in chop on ky lake.:Looks like a long shaft JP cheap manual one and less motor will run sweet,and about as fast as one wants to go in a 800pd Kevlar wee boat.