motor height confirm please

[rwl]

49.5 to 49.8, so no difference in WOT speed in the testing I have done so far. Doesn't make sense seeing the rpms are up at least 400, but must be slipping more. Hope to go to 4 blade and keep rpm's same by going down to 18".

Can't figure how some guys are getting 54 with same rig and prop? I don't much care though, just want it to work well, WOT speed is not high priority really.

[REW]

As the earlier post stated - the only thing that you have to do is to be able to have your prop stay hooked up during your routine running of the boat.
If you make a very tight turn and have the prop blow out, not a big deal - you can always trim down.

If - when working rough water, you get blow out, then you likely need to drop it a hole.

But that is why I suggested to raise it as high as possible and see how things work.
If it doesn't work, then start dropping and testing the rig, one hole at a time, until you have the prop hook up and performance that you want.

REW

[REW]

xxx

[rwl]

Okay its seems to be perfect. Slight venting , nothing trimming down doesnt take care of, I can get 6400 rpm, even with full tank couple people in boat. Works well for skiing, wakeboarding, tubing.
Tried an aluminum 4 blade, it wouldn't hold worth a darn pretty much any speed or trim, had it on for 10 minutes max and off it went. If it worked it would have been a spare, or LOTW's prop.
Tried a power tech PTZ4, its close, but still vents easily, the tempest is hands down best so far.
I'm sure I couldn't raise another hole, actually one down would maybe be right. I'll post picture, vent plate is high and dry, well high anyway.

[Gunflint]

I believe I have a very similar situation. Lund tyee 1850 with 175 Optimax. I think my motor needs to come up two holes.? What was your outcome??

Thanks!

[staylor]

Tried a power tech PTZ4, its close, but still vents easily, the tempest is hands down best so far.
I'm sure I couldn't raise another hole, actually one down would maybe be right. I'll post picture, vent plate is high and dry, well high anyway.[/QUOTE]

...and the trouble you have at low speeds may be from the PVS plugs on the Tempest needing to be swapped for a smaller size. A Tempest usually comes with the large diameter plugs installed- stamped with an "L" on them. If your prop was bought new it should have the L plugs- if used it may have no plugs in it and needs them put in.

I have a 21 Trophy Plus that is my general purpose prop- with just me and maybe 1 passenger in the boat and 4 "L" plugs its a great prop. But when I tried to carry 3 adults, 2 kids, and lots of gear the prop would vent way too much at around 20 mph and would fall off plane. I ended up swapping the 4 "L" plugs for 3 of the small "S" plugs and 1 of the "M"- medium size plugs. For a Tempest- which is more sensitive to PVS vents than a Trophy Plus ( which also vents over the hub)- I would suggest trying a switch to 3 of the "S" plugs and see if this doesn't cure the issues with pulling tubes.

As for your current engine height, you can check this pretty easily by running with just you in the boat heading into the wind at a 45 degree angle with about a 6 inch chop at around 4000 rpm. Play with your trim at this speed by going up until speed drops or rpm rises from venting, then trim down just a bit until you are at max speed possible without touching the throttle. Take a nice run of 1 mile or more, and see if you can hear the engine venting- it will pick up 100 rpm or so, then a few seconds later it will drop the 100 rpm- then pick up the rpm again in another few seconds. If this occurs, then you can go down 1 hole.

Also - trimming up does not necessarily indicate that you are running faster- the trim up should be such that you get to best speed with any throttle setting- and this best trim point changes as speed goes up or down. My Starcraft gets best performance from 30-50 mph with the trim at 3 for a Tempest and 4 for the Trophy props. For top end, I lose speed if the Tempest is trimmed above 5, or the Trophy trimmed above 6.

Your tests indicate that your rig and boating style is served pretty well with the Tempest- which has a 14.62 diameter, and 3 blades of large area with a moderate to high blade rake. I would suggest that if you want to try a 4 blade prop, look for a 4 blade with a full through hub exhaust, a diameter of at least 14.25 inches, moderate blade area and a high rake. The closest prop I know of to these specs is the Rev 4- but I believe it has too much blade area for your rig...but if you can find one to borrow for a day.....
Doug

[rwl]

Just got back from LOTW, put on about 400 miles in the boat in all types of conditions, here's what I found.

I was running the Tempest, I had terrible porposing when running in to the lodge, couldn't trim up at all really, boat was heavily loaded. I threw some heavy things up in the bow to help.

When running around the lake it did just as you said, you could feel the prop grab/slip/grab and the RPM go up and down. I could hear the prop vent quite often, even if I didn't feel it or really see much RPM change.

Rough conditions were worse, couldn't go real slow, it would drop off plane and vent.

I will be lowering one hole tommorow. Two holes definately too much I think. It really only runs well now at hole shot and WOT seems okay.

I have been thinking of what I gained by raising it and can't really think of anything, maybe better hole shot? I gained RPM but no speed, so the prop must be slipping more. I still have one prop from propman that hold promise, 4 blade RKR powertech, it was close but vented a bit also, but it seemed smooth and good holeshot.

Also I should try the PVS plugs, not sure which ones I have but I do have one out completely, I was under the impression they only mattered at hole shot.

Also should mention, can the motor being higher cause the boat to list? My boat is level when sitting in the water, but when it is up on plane it is low on the passenger side? I heard the transducers could also cause a trim tab effect, BUT, this is not something I've noticed before raising the engine.

The boat also feels loose, and washing around when driving, like its not planted. The back end washes back and forth in fairly smooth seas depending on how the waves are acting.

[staylor]

...1 hole. Also, if you get some PVS plugs I suspect the excessive venting will go away with either putting an L size plug in the hole that has no plug, or perhaps even switching out to 3 medium size M plugs. When you are running at low speeds barely on plane in rough water with a heavy load the PVS plugs do come into play, since for all intents and purposes the boat is doing a continuous hole shot. The same applies when pulling kids on tubes. Look closely at the plugs in the prop and you should be able to read the letter S,M, or L molded into the plug.

Also- there is nothing wrong when you have to run trimmed in fully when running in the above conditions. If I'm in the rough I rarely run above 1 on the trim gage at low planing speeds. Similarly, in these conditions the boat will be more sensitive to load placement- and if you're in a cross wind you may well have a distinct list (lean) to one side from either the load placement or the need to have the motor running turned a bit so you can hold a straight course. If you do need to move load forward and trim in for rough water then you also may get some "bow steer"- which often seems like a leaning to one side, but is actually the bow of the bow running buried and wanting to set it's own course.

As for your transducer- if its a skimmer type and it's not protruding below the bottom of the boat it should have little effect on anything. If you are running a skimmer transducer buried then it will have some effect since it acts like a brake. Many race boats actually run water brakes- which are simply two hefty metal rods that are lowered 4-6 inches below the bottom electrically by the driver when he needs to stop fast.
Doug

[rwl]

It's coming down one hole tonight, I think I need to split the difference. I have been back and forth whether to lower or not, or just drive trimmed down, but it would be in almost all conditions, loads, etc. It frees up the hull so much to trim up a bit, but then it vents too easily I believe. I've always had a problem with stuff like this, remembering what it was like before I made a change, bad memory.

I did have pictures of it now that it is raised but lost them in my iphone somehow, but the vent plate was completely visible, pretty high above the water, not at all like the original pictures in my first post.

I have the PVS plug I took out, I will try it back in. Along with the RKR which I know I need to remove a plug or two as it was slow out of the hole, no rpms on holeshot.

The boat definately has a lean/list to one side, in any condition, when on plane. When stopped it is level. It is annoying. I loaded heavy on the drivers side on the way out of LOTW just to compensate, anything heavy I put on the left side. My kicker is on the left, starting battery on right. My dad and my kicker are heavier than me and the starting battery, but I was very over compensating with my musky boxes, regular tackle bag which is 30-40 lbs and anything else we were hauling out.

I will have the kicker off and be pulling tubes and family duty this weekend after fishing for 10 days I need to do that.