i have rigged and de-rigged a donzi 38 zr F2 boat many times. same with a donzi 38 zr super v...all the same hull....standard, staggered. different centers. more x dimensions than one would believe. standard transom assemblies, ITS, and stand off boxes.
i kinda have an idea what works.

now for the speed gains....prop technology. once people got over slip numbers...running 1.32 vs 1.5 with very high x dim, ITS boxes, and 6 blades was prob worth 10 mph!

when i say de rigged....i mean pulling EVERYTHING off the transom and plugging it and starting over!

ps high x dimensions and prop technology also led to using number 6 dives in a 525 application...10 years prior it would have probably knocked off 20 mph!

most speeds people talk about are all BS!

and if you think for one second i would send a boat to a boat mag test with stock 525's!....more like 600+! or stock out of the mold hull?! props out of the merc box....i think not.

thanks for your input.
Offshoredrillin. ; Hull is a stripped out Cigarette 35 flatdeck,
tony toll`s old classic UK offshore boat "Adnania".

Mcollinstn/Audacity : getting the weight as low as possible and as near to the centre line as possible , from point of the
moment of inertia and C of G makes total sense. I guess the difficult part is trimming the boat (bow attitude) for moving
1500 lbs 3 feet or so, furthur forward. moving other weight etc.

If the kind of improvement mentioned on this thread,
35 fountain +26mph and the black boat 125mph then that really makes it worthwhile.
The engines have reserves of power wot 1200hp each at 5600 its just applying it in the best way to the water to give ideal performance.

I was interested in the thrust produced by like components and power in the two alternative
prop positions side by side / staggered.
I would have thought that staggered props, may by virtue of being in close proximity, work more efficiently to produce one larger combined thrust stream?
whereas side by side would be more independent thrusts.producing slightly less effect.
I may be thinking crap, props are 5 blade cleaver 17.5 x 36

forgot to advise prop position and ratio.
1:36 No6 Wets. Current prop center line , 31/2" directly below hull on each drive now Side by side.
Difficult to get prop center line level with hull boat without
raising engines and C of G.
thanks for all the numbers.

I have always wondered about this same question.

When i look at most raceboats with staggered configurations usually they saddle tanks along with possibly floor tanks for fuel. Is this to have a more stable relation of weight as it affects CG and as Audacity mentions moment of inertia as it the fuel is consumed?

I would think in a side by side situation with floor tanks as the fuel is consumed the CG is moving backwards towards the stern changing the CG. It seams this could be trouble in a stepped botom boat as it will ride differently as that CG changes.

With the saddle tanks a good portion of the fuel is in the area around the engines which as it is used is would be less of a change to the CG.

As far as weight being mounted lower in the hull -- i would think the saddle tanks would negate any effect of the engines being mounted lower. Due to the fact that the fuel would be located below the floor in a side by side...

I'm all ears on this as i look at a bare hull needing to b rigged....

Dave

a 35 foot boat with 2400 hp is too small of a hull for it...all that money in rigging....why not start with a more efficient better handling hull with stock power?

anything with over 750hp should b staggered....u will spend more time working on them than boating. it will make it easier to work on! it's about that easy.

does the boat have belly gas tank under the cockpit floor?

yes belly tanks. currently 2 x 125 gallons located approx under and forward of drivers/navigators feet. (cig 35 flatdeck).each side of center line.

video on U tube "mission impossible cigarette isle of wight" from memory, shows it used to run pretty well.
side by side, a few years ago, with 540`s then.

original engine 722 test on U tube "Merlin supercharged marine big block"
Weve got the parts weve got so its making the best out of them.

Lots of work to remove the cockpit floor, remove belly tanks, move bulkhead at the rear of the tanks forward, then shorten cockpit and build new stringer system. Then you have to build new hatches, repair the deck and put in a new transom.

I'm one for doing projects but that is getting to be a big one.