Prop/Impeller? & Hull Type?

[Mad Scientist]

Hello.

I am toying with the idea of building a boat - designed primarily for speed (with the possibility of towing things (skiers etc) if i feel like it).

I have the poweplant sorted, around 600HP @ 2500rpm at cruising speed, (max of 700HP, 3000rpm).

I need to know 3 things if you can help:

What sort of hull style would you recommend? Stability would be nice, I dont mind sacrificing some speed and handling for that. I am thinking along the lines of a traditional speedboat, as they are easy to get hold of. I would like room in the 'front' (i.e. driver & shotgun). Also, what material. I will be buying the hull, just fitting the engine.

What sort of propulsion system (i.e. propeller or impeller/waterjet) would suit this sort of engine best?

What size properller would I be looking at? I understand this is the tricky bit. If someone could point me in the direction of some formulae or other readimg material that would be great!

I am not going to build the boat yet - I am leaving plenty of time to prepare. As you can tell from the questions, I am a beginer

Thanks for your time.
M.S.

[duluthboats]

Pilot, co-pilot, and skier, isn’t 600hp overkill?

[Mad Scientist]

Overkill.... yeah

Obviously 600HP wont all be used to tow the skier (well, at least we wont need to turn people down because; "the engine isnt big enough to pull you. Sorry". hehe)

This is an experimental craft. I'm building it for the fun of it, not necessarily for it to be practical. The hull and driver will need to adapt to suit the engine - the engine is the reason for the project.

As I say, its an experiment, so the skiing is a semi-required bonus

Thanks!

[cyclops]

Bum a ride in a old 20' woodie speed boat with 400 to 450 hp. Then post again. your requirements should change.

[Mad Scientist]

What is it you have in mind? I have 600 horses to play with, if they dont get put in a boat, car or other, then the engine will be 'experimented with' by someone else - or put on a display stand

[mackid068]

Experimental? Sounds more like a cigarette boat (a go-fast).

[Mad Scientist]

It doesnt have to be fast, that was just my orrigional thought as I know 600HP is a lot. I couldnt think of much other than that. Building something larger and slower would end up costing a lot more.

Thanks.

[cyclops]

Could you tell us the information on the engine?

[mackid068]

Jet drives are fun...

[Willallison]

As cyclops suggests, you need a lot more info than you've given us in order to make any sensible suggestions.
Where do you want the boat to go - smooth or rough water?
How big are you thinking of?
How much $ do you want to spend?
etc etc etc

[Mad Scientist]

Hi.

Here is a webpage about the engine in general. It is not mine. http://www.gasturbine.pwp.blueyonder.co.uk/nimbus.htm

I have since found a number of webpages by people who have already made what I planned! See http://www.gas-turbines.com/squirt_2.htm and http://www.turbineboat.com/

My partner in the project emailed one of the builders, it turns out they prefer jet drives as they match the torque curves of their engines closer than a prop. I havent been able to get hold of the torque curve of the particular engine I am looking at, but how would I be able to verify what they say once i do get hold of it?

With regards to the water - it will go in the sea, by no means flat, but well under 1 foot high

[cyclops]

At .8 pounds of fuel per HP per hour = 600 hp X .8 = 480# per hour divided by 1 minute = 8# or about 1 gal/ minute. 2 minutes and you can be fish food. A 580 cubic pro racing engine can do the same performance with no restrictions on inlet air filters, outlet ducting heat problems or the huge area needed to fit it in the boat. Turbines DO NOT like the violent G forces a boat can force it to take. Age of the turbine blades and the fact it was never for marine use means it can and will blow up. 1 good 6" or larger wave at 80 mph could easily cause a blow up. DO NOT screw around with the old BOMB!! It can rip itself out of any mountings with all that RPM and the gearbox multipling the torque. These experiments are recorded in the Death Notices section of local newspapers. Try not to have people within a 1/4 of a mile when she is on plane. Piston engines will beat it safely every time.

[Mad Scientist]

Thanks for your concerns. As mentioned before, we are not building just yet, we at the feasibility check stage.

This was another of our concerns. which the other project member talked to a couple of people about. The responses ranged from "it hasnt happened to anyone yet - we dont take it out when there are too many waves to be safe" to "there isnt enough play in the bearings". Shock tolerances for engines is another of the statistics we are trying to get hold of, so I can see if there is any truth in it. There are quite a few turbine boats out there.

As a note, the turbine above isnt 'the' one we are going to use. We received word of a smaller APU, described as "bulletproof" - Another thing I will look into.

I understand the preference of pistons, bit I don't have a piston supplier who owes me a favour

It will probably end up making its way into a pure thrust 'funny car' eventually though :0

By the way, do propeller equations exist, or is it having an 'eye' for this type of thing that gets it? There is yet another project going on around here, plywood & lawnmower, you can guess the rest

Thanks for your comments.

[cyclops]

Get your boat insurance thru EVIL KENIVIL Underwriters.---------I still like the sound of a turbine boat winding up more than a piston. Safety is really tough in turbine anything. When the hair or skin starts to move around : STOP.

[cyclops]

Prop calc, are same as any boat & engine. HP @ rpm---max. torque @ rpm. Maby a few other spots of HP and torque to cover calc. A HP & torque curve of the engine and its total gear reduction or final governed output speed would make prop selection normal.