Tech help , given similar engines, 2 X(722) s/chargd, huber 1450s, drives (6`s wet sump )and props 5 blade cleaver 32 pitch. what performance % increase would be found by re positioning engines from present std side by side set up to staggered set up.
Old Cigarette undergoing major refit so serious work involved not a problem. understand staggered advantages from weight and C og G distribution , ease of working on engines etc but how does the relationship and distance apart of each prop in the water achieve maximum thrust, are their any technical papers orstuff that u know of or is it simply copying existing staggered set ups?
Boat originally appears to have once had a staggered set up in a previous life. So is it worth doing?

while i have tons of data to support answers to your questions....the easy answer is staggering them will make your life so much easier to work on them!!!

but what parts do u have? some forget to factor in the large expense of staggered exhaust systems.

cheers mate

Good point. their on Stellings, so would need two extension
pieces.
what I was really getting at, if all the main existing components were used, what across the water speed difference the staggered set up would give.
if Im pulling say 95 side by side would a staggered give 98 or what increase would be expected, if any, say in a typical Cig staggered layout?

Thanks,

nothing worth doing with todays prop technology for a performance gains on a pleasure boat. moving 1500 lbs forward in a designed pleasure boat can be detrimental. raising the drives further out of the water, changing gear ratios, and working something out with herring for prop swapping would the best thing to do for performance. if money was not an issue than i would do it from; i can't stand working on side by side engines! but then again some staggered engines are shoehorned in there too!

cheers

What hull are you doing it in? full cabin, half cabin, no cabin?

Biggest benefit is rough water handling. The roll inertia is much less since the rolling mass is closer to the centerline of the direction of travel. Motors are usually also able to be mounted lower in the hull for a given x-dimension.

Getting too much weight forward can be a drawback, too, so you have to get your batteries and fuel moved aft.

In smooth water, at sub-100mph speeds, I don't know that there would be enough speed difference to measure (assuming x-dims remain the same in relation to the height at the drive centerline).

MC

"The roll inertia is much less since the rolling mass is closer to the centerline of the direction of travel."

a misconception perpetuated by manufacturers that this is a good thing. waves have a far greater forces than those the boat can generate...totally unlike a car or airplane...loosing the moment of inertia in a boat can be a huge disadvantage.

Audacity, so are you saying by moving the engines (weight)twards center is not really helping.

in any application i love working on staggered engine set ups. the cost of adding very custom exhaust systems for a staggered set up can be....staggering tho.

for racing it's easier to balance the boat length wise. but it places the drives in place where the flow is much more consistent. being able to move weight around where you want it to met minimum weight requirements is always a bonus.

think of it this way: if you are holding 100 pounds and your goal is to manipulate (accelerate) it then you would want to be holding a dumbbell. if your goal is to resist an outside force to accelerate it? say someone giving it a bump. then you would want to be holding onto a barbell. your holding both at the CG but both have very different moments of inertia.

I wish there was a easy answer to this question backed with testing and proof. No disrespect to any answers on here, they all have helped my brain spin, but now I am thinking to much and its driving me crazy!!!

How did the 35 fountain go from like 85 to 101 overnight? I thought a large part was due to staggering the engines? Obviously higher X, props, etc. could contribute. Still there are not many 525 boats 32-35 running 101mph!!! (btw I am not a fountain fan)

Maybe Coolerman can chime in, they did an amazing job changing thier black thunder to staggered. They won at LOTO and currently run about 129mph! Full cabin 9'6" wide floating condo! Impressive. Stand up guys also.