What is wrong with this picture? This is my new old boat that I recently bought. is 6.0m with a 150 on it. About the most I can drop it is 45 - 50 mm. Will that be enough? I suppose it will have to be.
What is wrong with this picture? This is my new old boat that I recently bought. is 6.0m with a 150 on it. About the most I can drop it is 45 - 50 mm. Will that be enough? I suppose it will have to be.
Hi Cheech
It does not look too far off but how does it run?
I a tend to look at where the cav plate (and your permatrim) sits in relation to the water surface when you are travelling at a cruise speed plane to higher speed plane and the motor is trimmed out so that the steering is in the sweet spot ie light and easy to move.
My experience has been that it seems right to me if you could get you fingers between the water surface and the bottom of the cav plate and certainly the permatrim as it extends so far back (if your arm was long enough that is,)
Your thoughts?
Cheers
Chimo
What could go wrong.......................
Yeah looks like a great starting point if it were mine I would hope to get another half inch or better higher, your WOT revs and GPS speed will tell all if you know your prop pitch.
If you are looking to kill all venilation/cavitiation you will also kill a good setup.
Nice looking deadrise - what is it?
cheers fnq
Last edited by FNQCairns; 31-03-2007 at 12:41 PM.
What's wrong with this picture? Well apart from the foilnot a lot, is the foil neccessary? ah maybe we'll forget the foil for now!
Wouldn't be going down 45-50mm, maybe one hole only (obviously can't go up) to see what happens but then what is wrong with it anyway? Apart from the foil
I wouldn't say that there is anything wrong with it without info from a water test. My Yammy sits a little higher than that again... and is quite happy there.
It all has to do with how the water comes out from under the hull. The water tends to rise up immediately after the hull pases over it. Each hull is different though and the higher the deadrise the more it happens.
The only reason you would want to go down is if the prop is breaking loose prematurely when you try to trim it out.
Every inch you lower the motor will cost you about 250 rpm at WOT as it is extra drag.
FNQ... Here's a deadrise for you... (The ducer angle wedge was modified after this photo was taken)
cheers
Trueblue yes that is sharp, what angle 26?? - ocean going limo
cheers fnq
Well,, I was not expecting that response. But is appears to be unanimous.
I was convinced it was way too high.
The problem with it is that when flat water and the boat is straight it is fine, but when doing even the smallest left turn or if the boat is leaning left down due to wind, the prop slips. ie the revs go up and you can just tell it is not biting properly. I had put it down to being too high up. Is way higher than the motor on my 18fter. By the sound of it, that may be too low!
Due to the slipping, you you think it is worth dropping a bit and sacrifice a bit of performance?
Cheech
Kerry, I tend to agree with you on the permatrim. Seems every boat I buy has one and I have always removed them. Maybe that is having an effect on it and may reduce the problem if it is removed.
FNQ, the boat is a Swiftcraft. Been told the deadrise is 21 degrees.
How much above the transom is the motor sitting?
It probably wouldnt hurt to drop the motor one hole and its easy enough to do with a block under the skek and by lifting and lowering the rear by use of the jockey wheel.
Before you do it tho what condition is the prop in?
Also depending on what breed of prop you have some just dont like being out of the water, if thats the case or the prop is damaged may be get it fixed before the next step ie lower one hole
Good luck with it
Cheers
Chimo
What could go wrong.......................
Mine! Would drop it one hole just out of curiousity as no there's no harm done to see what the affect is. While down a hole would knock off the foil and see what the affect is? Surely one would notice better or for worse?
The other query is (as always) is what size prop and what WOT?
Hi Kerry
Shared thought processes me thinks / ?
Chimo
What could go wrong.......................
It does sound as though you need to go down if you are getting that much air, bit of a shame though, hopefully it will not be 50mm needed to fix.
Interested to hear what happens if you do run it with just the foil removed.
cheers fnq
A new rig .... does this mean we will see you on the wide grounds more often now Craig
It is a 17p stainless on the 150 yammy 2st. There is a bit of damage. A small chunk out of one blade on the outer extremity in the shape of a small bite about the size of a 5 cent piece that has had a third of it cut off (if that makes sense). Considered filing it a bit to smooth the outer line of the blade. Do you thihk it would make a difference? I didn't think it would considering it is fine in a straight line.
Sits up about 45mm, or about 2 holes.
Cannot give rpm stats yet as I have only had it on the water once, so still getting to know it.
Mark, this doesnt mean I will do all my trips on my own boat. Besides, I am still owed a cobia
Hi Cheech
Yeah went through this a while back as most here would recall and I had exactly the same issue. Would be fine in a line, but hand down the slightest amount and a cavitate she would go!! Here is my 2 cents:
a. Get on the phone to Solas props down the gold coast and tell them what size boat, engine etc...then ask them for a prop recommendation. My prop is way out and the engine literally overpowers the prop.
b. At cruising speed, calm water, have a look over the back at your foil. Mine was under the water by 1/2 - 3/4 inch. raised the engine and it is now level with the top of the water.
c. Try trimming all the way in before you turn...this may help a little while you get it sorted.
Anyway, I ain't no expert, but that is what would do next.
BilgeBoy
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