Boatlesss

we all will be watching how they work on a boat this size and power, what's the cost, 35K ea. plus transom assemblies, steering and such. i think Jim Sikes spent close to $90K for a pair when using used transom assemblies to complete the XPower package. sounds like a bargain when compared to the reliable arneson direction marsu is going in that cost much less including the transmisions

delsol

very interesting build, looks a lot like the hull I have. Do you have any better shots of the transom?

Marsu79

Delsol, Still not finished. Now my area of concentration is the transom and the propulsion system.
Will post once I complete them.

Rik

Contact me if you need help.

Rik

HabanaJoe

Just my 2 cents, unless you really overdrive the heck out of those the boat is not going to fast, no prop speed I say 50-60 mph. The other problem is those engines are huge (14.5 liters) if they are what I think they are? They are size wise smaller than a 3408 Cat but bigger than an 8-92, I think once you marinize them you would be better off with 650, 710 or 750hp 8-92's and they would weigh less? I'm sure you can get some good HP out of them but stock - too slow turning and not enough Hp for the weight to be a go-fast performance type drive train.

Sorry, Like I said my 2 cents

Marsu79

I can see what you are trying to say HabanaJoe and you are totally right.
But, from another side, I have an idea that I am trying to make work and have just gathered the components. All my focus is on revving up and keeping torque, but I am having a little bit of trouble concerning the propellers data, as manufacturers do not have info I could work with in my calculations.
Let's cross our fingers for good performance.

stirling

I ,m trying to understand the numbers you have , what exactly is the pitch number you calculated ?
In the info you said 28,5x 57 ,but 57 pitch seems a bit odd.
The rpm your motors are turning with the overdrive you want to use seems like your propellors are pretty big in diameter...I think you have to reduce that to 19-21 inch max because your boat is 46 ft long ,and 32 ft water line length ??? or is that a type error ?? anyway its not a 10ton cruiser your buiding , are you have a weight figure already ?
also the ratio,s between 1 th gear and 2 th is a large gap .
I,m not sure why the gap would be that big .. I also have 2 speed trannies from ZF ,1 th gear is 1,30 and 2 th gear is 1:1 , however I have a 3500 rpm max .

HabanaJoe

Marsu, I wish you all the luck but going fast is the same today as it was in the 1930's, you can't offset lack of prop speed by adding pitch, it just doesn't work that way. It takes X dia to make enough thrust to push the boat, the faster you turn it the less Dia you need to make the same thrust. Yes, at lower rpms the prop will slip like crazy but it will catch up.

Take any 40' plus boat running Bravo drives, those little props can push a big boat pretty dam fast!

I tried what you want to do in 1983-1984 when everyone said "it's diesel, you spin a BIG prop slower and you go faster" When we hit a wall for speed they say "add more pitch" - they were all wrong! Smaller dia, less pitch, faster turning got us there.

I will agree that with today's 4, 5 & 6 blade props there is huge difference than 3 or 4 bladers of the day but hopefully it will work for you.

hallj

Do you mean a hydrostatic transmission like Eaton or Sunstrand?
Then a hydraulic motor for each drive?

Jeff

HabanaJoe

I think you mean like a hydrostatic as was mentioned above? If so back in the late 80's a boat from the UK named Diesel Dancer (there were more don't recall names) used hydrstatic transmissions in front of Speedmaster drives.

The advantage of them were you did not need a 2 speed tranny, even though at that time no one had a 2-speed tranny. You could rev up the engines with the throttles so they were in a good rpm range to make boost and then start locking up the tranny clutch packs. Once on plane you lock up the trannys and go!!!

They are also very good in turns as you do not need to use the throttles to slow down, just ease off the tranny pressure and props slow down but rpm stays high and you maintain some boost so when you apply the pressure to the clutches you have rpm and boost waiting for you - they could out accelerate most anything in a turn back then.

Like I said earlier, most of what needs to be done with diesels has been tried and perfected, you just need to take what was done and apply modern technology to it because the wheel will always be round.