Ok so the Backdraft is getting a lifter but need some advice on the initial alignment,

1: on the picture below (crap i know but serves it's purpose) what would be considered the neutral "TRIM" line (straight through propshaft) as i have been given many conflicting answers A or B ? ... B seems the most obvious to me but most say A

2: When we initially tried a manual lifter we found the engine had to be considerably higher due to the additional 5" setback to get the same results, with this in mind what would be the neutral height ie: halfway to allow us to be able to get the required range or do you setup at max up or down ?

BTW it's a CMC hydraulic (pl65 i think) and any help / advice would be appreciated

Adrian

For what it's worth (Most prob not a lot ) I was told to use a spirit level to ensure the step was horizontal by adjusting the jockey wheel and then trim the engine to get the prop shaft horizontal and in that position you would have "Neutral Trim" or in other words "A" on the drawing..

The question can be likened to the classic question is a Zebra white with black stripes or black with white stripes.
Depending on your perspective & point of view it could be either one. The important thing is to establish your datum (wherever it is) and record your changes from that datum. Key point is the number of units from that datum to finding the “sweet spot”
That said I tend to datum around the designed running “Neutral” In your example that would be “B”.
On the Midas it’s set as Propshaft & Last 3 foot of sponsons both in line (level), this gives it about a 4 degree running nose up (tunnel angle)

Dont forget we have ACY (adam) resident I'm sure he will chip in and clarify

Mr Bluefin that really does prove that you have too much time on you hands (still at least its more creative than Mafia wars ) ..

As far as neutral trim goes then i think i'll set at "B" and use that as a datum and mark + or - from there, At least Ashleigh will have something to work to rather than just up or down a bit from somewhere in the middle

What about the lifter though ? i was going to set it so that at its lowest point the bullet was about 1-1, 1/2 " below the line ("B") which without the additional setback would probably equall adout 3" below .. any thoughts?

PS. above pic now printed and in the 'secret' file :)

[quote="foolish"]
What about the lifter though ? i was going to set it so that at its lowest point the bullet was about 1-1, 1/2 " below the line ("B") which without the additional setback would probably equall adout 3" below .. any thoughts?
/[quote]

maybe just a tad higher - Everybody has their own thoughts on lifters & setting up, that’s what makes it so creative. ( read that as taking ages)

I tend to prefer keeping things mid point so for a lifter my max lift in anger would be about ½ travel or mid point. All the weight & leverage of the extra inch or two just puts a little more stress & strain on the equipment.

I would certainly go with version 'B'. The straight line (CL) from transom to first step is all you really need to measure. If projected forward to the next step there should most likely be a small gap. (i.e. the 3 points will not be directly in line) - which is the rocker across the steps and helps to get a bit of release.

As Jon says - take your choice and stick ot it - make it your datum.

Difficult one with heights and varies so much boat to boat - so your knowledge of the boat will count for more than anything. I'm more used to setting up for 3C boats with lifters but I would be looking to run maybe maximum of 3 inches below keel to a max of 2 inches above. Then I would raise that all by no more than an inch for the set-back.

But got to consider speed of boat, weight of boat, engine trim required, propellers etc. I believe there are always benefits to lifters, especially with stepped hulls - but it there can be a lot of set-up work needed to make the most using lifters.

Have fun

Thanks to all for the advice, The boat is now in the garage and have started the rebuild for this season, suprised how much easier it is in the warm compared with last year out in the rain and snow under a tarp ! quite a few mods to be made so need to prioritize as we still need some testing time before Allhallows

My opinion is just number the scale - datums don't actually mean anything, and it make me laugh when people say " I had it on 4 on the trim!" when 4 might as well be replaced with tomatoes - it make s as much sense. Calibrate both scales and when she's happy with where everthing is best you can either re zero it (probably more confusing) or put a little mark on the guage. All IMHO of course!

Call it a Datium

Told you it wasn't worth much