motor height

[JoshKeller]

Confused a little on motor height. I redid my transom (new wood, etc) and put the motor back at the original height. I'm thinking the motor is too low, causing my boat to run 22 mph no matter if its just me (220 lbs) or if i load the boat down with 3 of us thats almost 700 lbs.

should the straight edge be even with the edge the way its show in my pictures, or should i bring it up to be inline with the water intake? Ive played with the trim angles and noticed there wasnt a huge difference either way - less than 1 mph from trimmed down to full trimmed out. the boat runs well with all of the angles, except trimmed out completely, where you can actually feel the drag on turns. any suggestions? bring it up one hole maybe?

 

[dhoganjr]

It looks low from what I can see. I'm guessing you have a lot of water spray also, if so it is definitely too low. I want the lip above the bottom edge of the hull on mine. Try to aim for the straight edge to hit about where the pin is that holds the front of the grates in. Looks like you can raise it a hole and let the trim out 1 or 2 holes.

Think of it as you are moving forward the water coming out from under the boat is rising. The farther back the shoe is, the higher the water will be when it hits the intake. Too low and water goes over the lip creating drag causing the front to plow. With the motor trimmed or tucked all the way under it increases the plowing.

Most boats can be set at that height to run, some will not. That is where I start and then adjust from there. At some point it will have too much cavitation during chop and hard turns, then you lower it a bit.

 

[dhoganjr]

This was where I had mine set, it would run at that height but had a little too much cavitation in heavy chop. I dropped it a 1/4 of an inch and it is perfect. It lines up with the pin now.

 

[buckeyeBEN]

I agree with dhoganjr it does look low but the pic doesnt show enough of the hull.

I had similar issues and had to do a bunch of measuring and math. I ended up with a motor mount to help fine tune the height. I also considered a jackplate. Depending on the water conditions, you could adjust.

One last thing you should consider is one of those plates that you would weld on the bottom of the hull to bridge the gap between the foot and the transom.

 

[JoshKeller]

moved it up one hole and came to this location... hows this look? I noticed that with the old location, the boat really didnt have any lift no matter what trim angle. The front definitely plowed water.

 

[dhoganjr]

JoshKeller » 21 Aug 2014, 18:44[/url]"]moved it up one hole and came to this location... hows this look? I noticed that with the old location, the boat really didnt have any lift no matter what trim angle. The front definitely plowed water.

That definitely looks a lot closer to were it needs to be, need to run it to find out how it is going to perform now.

I would also recommend straightening those grates, that will severely disrupt the water flow, probably lose 1 mph just from them.

 

[dhoganjr]

If it cavitates too much try letting the trim out another notch. The trim is the easiest to adjust and you can do it while you are on the water trying several different spots during one run.

 

[JoshKeller]

will try it out tomorrow and report back. I will work on the grates this weekend, I bent them last trip out and just havent had time to mess with them.

 

[buckeyeBEN]

All these guys are right on the money.
When you are running it, I'd suggest doing some figure 8 to creat some chop. You want to see of it's going to cavitate.
I feel your pain bc sometimes one hole is too much.

Looking forward to hearing how it performs tomorrow.
Good Luck.

 

[JoshKeller]

do i really need to worry about the chop if the river i fish is small and is rarely if ever choppy?

 

[dhoganjr]

JoshKeller » 21 Aug 2014, 20:44[/url]"]do i really need to worry about the chop if the river i fish is small and is rarely if ever choppy?

Usually if you have cavitation in chop you also have it on hard turns, which would be my main concern. You don't want it breaking loose in a hard turn especially during an emergency maneuver.

 

[JoshKeller]

dhoganjr » Yesterday, 22:00[/url]"]

JoshKeller » 21 Aug 2014, 20:44[/url]"]do i really need to worry about the chop if the river i fish is small and is rarely if ever choppy?

Usually if you have cavitation in chop you also have it on hard turns, which would be my main concern. You don't want it breaking loose in a hard turn especially during an emergency maneuver.

wont get to test until tomorrow, but theres no doubt the height the motor was before, you could definitely feel the motor grabbing the water on hard turns.

 

[dhoganjr]

Hoping it does good for you. There's about an inch between hole adjustments, sometimes a quarter or eighth of an inch adjustment is needed to find the sweet spot and get everything out of it. I slotted the holes in mine to get the Fourstroke lined out. With the 250 I filled the mounting holes in and redrilled them, mounted, tested and repeated till I found the perfect height.

 

[JoshKeller]

Took it out today. Middle trim hole cavitated. Fully trimmed in it picked up the boat onto plane and ran good but still pushed water. Will try and drill out the holes and lower it 1/4" or so so I can use more trim.

Boat still ran 22 upriver and 23 down. Boat definitely slid more into turns

 

[dhoganjr]

1/4" should put it where it needs to be. Have you sharpened and shimmed the impeller recently. It doesn't take much for you to lose a couple mph.

 

[JoshKeller]

Yes sharpened and shimmed up.

 

[JoshKeller]

adjusted again today and split the difference between the two mounting holes. undid the top bolts, lowered the motor some, then used the floor jack to lift the motor in between the bottom and 2nd up holes. Used the holes in the transom to hold the bit steady and it went right through. I figure it lowed the motor 3/8" or so. will test again tomorrow after work if time allows.

 

[JoshKeller]

Ran it today. No cavitation. Got 23 mph up river and 25.8 down so that's an improvement. Before I assume the foot was dragging and limiting to 22 all the time. I'm getting a little spray but it may be normal or not enough to worry about. Heres a video, would you change anything? Another question - in terms of running shallow, it makes sense to me to not want bow lift, as that would lower the back of the boat. do I want it running pretty much level through the water, and not worry to much about the spray coming off pretty much the entire boat except maybe the first 4'?

https://www.youtube.com/watch?v=tJvGpFewIos&feature=youtube_gdata_player

 

[dhoganjr]

Good improvement, if the spray is not coming in the boat I wouldn't be to concerned about it. You might have to put a splash plate on there.

After running there did you try trimming out 1 more hole. It is ok running flat, if you got the plowing under control, but the more of the hull that is in the water the more drag it has cutting speed.

Without power trim you have to find a happy medium though, down for takeoff, up for on plane.

 

[JoshKeller]

It ran good on the middle trim hole. It cavitated on take off when it was on the third hole. Does the hole shot aplear to be acceptable?