MikeyFIN

Cummins/FPT 3000 rpm and Yanmar 3300 at top hp.
The governor kick in on the FPT at 3150 as stock at least.

stirling

They didn,t mentioned how much speed was lost ,but I guess it was very little ,but when they added more torque/horsepower ,the least expect was a little more speed.
but I do also think the gearbox they used with the Yanmar 440,s is the same box I use in my boat with the 1,30 in 1 th gear and 1:1 in second gear,and not sure if ZF offers taller ratio,s than 1:1 ,but I see what you mean with losing prop speed ,and maybe Scotty knows if they were using the 2 speed boxes with the FPT,s or not ? maybe they opt for a single gearbox with a ratio under 1:1 ??? if so the circle is closed

scotty uk

i think they ran single speed boxes in the race boat ,i know it used to struggle to stay on the plane on the rolling start,they also added a chine/sprayrail to the rear that buzzi says is a no no.

stirling

So they wanted more sternlift ...,I wonder why ? the boats angle was ok,wet surface also,I mean ,its Buzzi,s design ,if the boat needed more stern lift ,he would have been added lifting strakes ,or could it be for the 125 lbs extra for each engine ? Nah

Now I begin to understand why the Cummins combo was a little slower.

Scotty,have you got the 2 speed boxes for in your boat ?

HabanaJoe

I would have said if they had trouble staying on plane, not getting but staying they are running steep OD gears. It's just like us little dia props lots of rpm can't carry the boat going slow and it falls off plane. With 1:1 gear and all that horsepower she would have large dia props and stay on plane at very slow speeds. Liken the small props to a large heavy outboard boat, they can run like hell but have no slower speeds, they either plow or up on plane running.

Why did they loose top speed? I just contradicted everything I thought was going on which was too slow prop speed!

I wish we had some data because it still seems to me the Cummins is 3,000 and the Yanmar is 3,300 and both should have about 150 in droop, right??? So, with equal gears the Cummins boat could be slower because the pitch they may have added doesn't equal the 300 rpm drop???

It's all speculation at this point but I can't see the two boats more than a couple mph's apart????

I can't see the race boat running 1:1 because that is just not Buzzi, all the boats ran OD's. Figure the math of how fast they go and what the engines turn and there are not props with enough pitch to go as fast as they go - this is basic math, no insults just can't be done with pitch.

Joe Gere

stirling

I bought 2 ZF 2 speed transmissions from Buzzi,they came out a xs type boat with diesels ,1,30 and 1:1 gears ,but it was a pleasure boat running 78 mph with 2 x 440 Yanmars,the owner changed to FPT power ,and I didn,t ask what gearboxes he were going to use ,If I calculate back from that 38 xs boat by knowing speed and ratio,but no slip and assuming the trimax to have about 10% slip,they must been turning a set 28 pitch props,so Joe ,assume he turned up the fuel on those Yanmars to have around 500 hp each and the rpm comes into the governer ,what will happen if you put on 1 or maybe 2 extra more pitch ? will the boat gain some speed now because nothing changed regarding weight,or less rpm ?

Are there manufacturers that offer overdrive style gearboxes ?
I,ve seen a PRM gearbox with 1:1,1 overdrive ,but thats not much ,and don,t no if PRM is still in business ?

I found on ZF,s page some gearboxes with ratio,s around .80 -.85 ,I guess I answered my own question

tony davis

Better get yer finger out, or the "bombay bum basher" is on you!

scotty uk

td,when the braces are done its engines in,for those who are confused theres a bet if its not in the water by 7th feb when theres a small local race then i have to pay for a meal at an idian restaurant

aquafun

We're rooting for you Scotty you can do it, it will be great to see the boat in action and better still it might spur on other P1 entrants to turn up

Going by your Avatar would I be right in assuming your XS was the boat used by Peter Dredge etc to set some endurance records around 2000-2001 time
I know there was an XS in the RB and CTC endurance events last year and I have always been surprised more XS boats have not become race boats as they do seem a good way to get out racing

No doubt the Yans wick will need turning up as the boat must weigh in around 4300KG+ and in order to achieve the optimum 4.5KB per HP around 480hp apiece will be needed in the SuperSport P1class

scotty uk

hi aquafun thanks for the support,the xs that dredge and co were in is dean gibbs one going lean,mine is sunseeker race teams pr boat .im gona change the pic know