500 hp and 75 mph, they should all be ashamed of themselves and embrassed to even print that - it is a joke.

I don't mean that to be mean or insulting but that is exactly why diesel performance goes no where in this country.

Ask Ron Hicks, Bernie Rice, Brett Archer we did 74 mph with a 23' Maelstrom in 1989 with only 365 hp. We weren't smart enough back then to be able to use all 365 hp either, we really only put about 295 to the water!!!!

I know that because a couple years later once we had the electric dyno we were able to control the loads better and take our in boat readings and run them on the stand - we were always very schocked how little hp you actually made in the boat.

I very curios what they say when they do a 30+ whit twins

I have a 32 hustler putting 640hp on the xr drives ,so hope to get 580 in the water and see 65 mph @ 3650 rpm hope to hit the 70's if they are dailed in ,and are more then happy whit that number !!

What I don't understand is 500 hp is 500 hp. It is at a lower r.p.m. but can't that be corrected with gear ratio to get the prop speed where it is needed?

Where is the loss in speed coming from?

Is it because of the limited range of speed in the motor that you can’t correct the prop speed?:confused:

Yes diesels need more than one forward gear to make speed. Weismann has 2-6 speed gearboxes that can be offset so the firewall doesn't have to be moved. IMCO's setup only had one gear.

Eliminator installed the new lightweight 480hp Cummins 5.9s in their 43' V bottom but they didn't use multispeed gearboxes either. They only ran 73.

Wildman - you are 100% correct, HP is HP and yes you can compenstate with gear ratios - I'ved talked about this for many pages on here before.

Boat speed controled by prop speed within reason, pitch can only go so far before it just doesn't work.

So, you can go as far as you can in pitch and then need to add prop speed.

We found you just couldn't load the engine enough to use all the available Hp. The lack of horsepower at the low rpm's prohibited the boat from being able to get on plane so you needed a smaller prop for planing and then like I said you had too little at the top end.

That is why multispeeds work well with the diesels.

Sounds like heaven
 

Joe,
I was down in the Yaeyama Islands last week. One morning I was at the Ishigaki Island (the main hub) commuter terminal 1st thing in the morning. Imagine this.....32 boats engines ranging from 800hp to 1500hp mostly pairs with a few triples. ALL WARMING UP AT THE SAME TIME! The low idle apocalyptic sound. Now thats my kind of music.:drink: I went along on a check ride on a boat we built 2 years back. They were having problems with their stbd tach. 60' low slung aluminum commuter boat. 90 pax but we only had 15 pairs of cheeks in the seats. Pair of 1300hp 140mm bore V-12s on jet pumps. Cleared the outer breakwater and ole boy slammed the sticks. 35 knots for an hour to Iriomote Island. 15 minute turnaround wait and 35 knots all the way back to the Ishigaki Terminal. That harbor everyday is worse than a Home Depot parking lot on a sunday.:eek:
Ed:evilb:

so who's going to actually build a project, do all the R&D and show us how it works. Otherwise it's a mute point

been there done that, too slow NO FUN. We reached almost 75 in a side by side application, heavier boat (43 NorTech) but with the 480hp Yanmar's.

Jassman, if I had your money I could do it but I don't?

It's not like it's not been done before, it has - I have done it so you got me on a roll now!

7X champ is on here, he's seen our fast diesel boats, Craig Barrie and Bud have been on them almost 20 years ago (1990) and into the 80's mph was not an issue. Just go to Italy and you'll see plenty of fast diesel boats.

R&D, it's been done, all the people you've dealt with have been to blind to see what is in front of them everyday and how things work. I'll be really bold here and say just because you can build a fancy boat that sells really well doesn't mean you know how to engineer propulsions systems. Most Boat builders I've met over the years know little about engines, they call merc or whoever and say give me 2 600 hp engines and slap black drives behind them with 1:50 ratios and start playing the prop game. That doesn't work with diesels, that simple.

What scares most people is doing something they have never done so they just go with what they know and not what they are unfamilar with.

Like catmando said Weisman has gear boxes, ZF has gear boxes and you can use a Lenco if you wanted to R&D something.

You know that if you had put Weismann transmissions in that boat you would have run close to 100. Hell even the 2 speed Lencos would give you at least 80.