strut adjustment question..

[lenny]

Hi,
It is easy.
This is how I look at it,
If you go up on strut and add trim up or down you lose power and speed.
And if you go down with the strut and add trim up or down you lose power and speed to.
But if the strut is level with the sponsons and it is trimmed level that is all the power pushing forward with no loss,
Except for some drag of water and air.
And than it is riding just on the CG settings of the cells to keep it on the water and air mix under it.

[tlandauer]

IT is a compromised endeavor: The lower the strut, the higher the rear is riding, but the tunnel is still trapping air, as someone said in another thread---probably the one thread that confused you, the air trapped need to "fart out" ( his words), this cycle plus the awful untrued ride pads makes the MG go Wah-wah-wah. Raising the strut lets the rear pads to sit on water more, the negative thrust angle helps to point the bow down, remember, the floor of the tunnel is not parallel with the water line, as the boat is moving forward at a good pace, the air underneath generates a great deal of lift, this "cushion" of air has to escape and we are talking about how much we let it escape without slowing ( too wet) or blowing over( too dry).
On the MG, the riding attitude correspond to the height of the strut, what I mean is we generally talk about a certain height in regard to a certain speed we like to see the boat to run, I feel that actually for different speeds the strut needs to be in different places. Case in point, mine would porpoise in a certain throttle range, then it will calm down ( As I increase the throttle input) . If I adjust for that particular speed, then later in the throttle curve it will bounce again.
I should add that the angle of attack which is partly generated by the thrust is crucial: hence the recommendation to add a bit of negative in the prop, think of it as a token of insurance to limit the AOA.
Now I can be completely wrong...

[kwiktsi]

I realize the trim is basically wasted power/thrust, but have experienced cases were just a little bit one way or another has helped increase speed. Be it a cog issue or what, I don't know as it was a long time ago, but I have seen it help in the past. Now, what you say about level height and trim, then adjusting the cog from there being "ideal". I would think the same (or the strut just a touch lower in my experience with my bk). But again, that goes against what the common mg "fix" is. As said above, the air needs to exit which is part of the reason it bounces- wouldn't dropping the strut and raising the transom only help that?

Sorry for confusing things bringing the mg into this, it really was a question about strut adjustment in general, but the mg came up because that is what I am currently tinkering with and the recommended fix goes against any of my past personal experience, so I figured I'd bring it into the equation.

I will check out the link when I get home. At my sons school play right now. Thanks guys, lots of input here.

[kwiktsi]

Ok, just checked out that link. That is exactly as I thought it worked but I have read here and several other places that it is the opposite and raising the strut makes it run looser..

[tlandauer]

....wouldn't dropping the strut and raising the transom only help that?

That was my thinking at first, but I think if the pads aren't sitting enough on the water, the lifting/"farting out" and slam dunk cycle is exacerbated, lowering the ride pads ( raising the strut) plants the hull and by pointing the bow down ( neutral or slight negative thrust) , the floor is more parallel to the water line and the air that is trapped escapes in a more controlled/continuous fashion. To me, only when the hull is riding well could I begin to consider speed.
I am not recommending to run the hull wet, but what I have experienced and witnessed is the all -too-often attitude like the Concord Super Sonic jet liner ( old farts like me still remember that plane ) taking off!

[lenny]

Well also if you look at those same several other places,
The CG is way off the chart with were the cells are placed so far forward in the hull.
Than where it should be setup in the hull and I am talking about the MG1, MG2, MS29, BJ29,They are all the same hull,
For the most part of the mold that they came from.

[Heaving Earth]

Dropping the strut just puts more load on the motor. There's also that to figure in.

[jwray]

Dropping the strut just puts more load on the motor. There's also that to figure in.

Along with this statment if the lift of the prop cant overcome the wieght of the hull then lowering the prop loads the motor reduces RPM, slows the boat down a hair and calms it down a little.

[Rocstar]

Along with this statment if the lift of the prop cant overcome the wieght of the hull then lowering the prop loads the motor reduces RPM, slows the boat down a hair and calms it down a little.

And increases current draw.

[kwiktsi]

Along with this statment if the lift of the prop cant overcome the wieght of the hull then lowering the prop loads the motor reduces RPM, slows the boat down a hair and calms it down a little.

See, that was my thinking too- if the strut was TOO deep, then it would load the motor, slow the boat, etc. and lifting it would help things out, but I am still under the impression that once the sweet spot is found, lowering it will make it run looser (like is shown in the diagram linked above). Confused...

[Speedracer128]

Interesting. So I assume using one hull as an example like the MG. depending what motor, setup, batteries, prop, ect would call for diffent strut height and angle

[kwiktsi]

I have another question since this is being discussed. On a boat such as my Pursuit which comes stock with a 2 piece shaft, the drive dog thrusts against the strut vs. the motor like it would with a 1 piece shaft. Will this change how the strut/stinger adjustment affects things since it is changing the thrust line of the boat?