Bulding new Boat called bolt -- need help

[computerwhiz2]

okay so this summer I am going to try out a boat design.

I am going to take a car or large marine engine and put it inside a 21' or 18' seadoo challenger and mount it in the center (you know the spot where they want you to store skis and stuff)

I am planning to use a large engine like a 6 or 8 cylinder corvette/mustang engine and marinize it with a new alternator/starter/ect.

anyways - so I need to know what additional work needs to be done.

on another note I am going to use a manual transmission to shift gears while underway (I know there is a large debate about this but I think that with enough speed and HP you could shift gears. it would go ilke this
?Start in gear 1 (probably gear 3/4 on a car) and accelerate to crazy plane
?To save fuel economy and lesson RPS shift to 4th/5th gear
?To achieve maximum fuel economy and speed shift to 5th/6th gear

I can drive stick and shift gears fast.

So i need people to help me learn how to mount the engine - and to choose a different pitch impeller (if that is possible) to achieve maximum fuel economy and save RPMS -

If anybody has done something like this before let me know

additionally could I use an automatic transmission for future builds (I have heard that some bearings could possibly break- is there one that won't for marine use - will it switch gears underway) - what about semi-automatic/paddle shifters.

also if i go really fast will I need front ballast tanks to keep the boat from "flying"?

 

[andgott]

Re: Bulding new Boat called bolt -- need help

okay so this summer I am going to try out a boat design.

also if i go really fast will I need front ballast tanks to keep the boat from "flying"?

Step one- Contact a good naval architect/designer.

Step two- Update the life insurance policy to provide for the family after you're gone.

 

[Woodonglass]

Re: Bulding new Boat called bolt -- need help

On iBoats we always try to advise against unsafe practices and THIS is definetly an unsafe practice. You REALLY need to do a LOT of MARITIME investigation and studying. You really have NO IDEA what you are about to attempt.

 

[oops!]

Re: Bulding new Boat called bolt -- need help

hi....welcome to iboats.

as you nave mentioned.....there has been much debate about a transmission in a boat...after all.....that is the only thing you are trying to achieve here correct?

well......while i will not discourage you....I will say that if it worked, it would be in standard practise today. but it does not work.
this idea has been tried, and tried.

as far as the hull design ......what you will need to do is to add a thru hull prop/shaft with a rudder.
designing it will be a tricky thing, as tollerances for the shaft are crutial. since the challenger is a jet boat....you would have to remove the jet, and glass in the hole.....then design your thru hull, fit it with a cutlass bearing. the problem here is the angle of attack. it is crutial for any performance of any kind.

may i suggest that you start with a mid engine true inboard. it allready has the shaft, rudder, the proper angle of attack for the hull.

then you can fit your transmission to that. older inboards are relativity cheap and have every thing you need.

the other thing you need to know,,,,is that there is a difference between marine and auto,,,,,its a big difference,
marine engines are fitted with special spark arresting equipment. if fuel fumes escape thier systems. and come into contact with a ignition source, they will explode like a bomb.
it is this reason that we are very careful to make sure that only marine approved parts are used.

you mention that you can shift gears very fast....thats cool, but i dont think you are aware of the speed needed to keep the power to the prop. there is a big difference between a car using forward momentum to allow for gear synchronization and a hydrodynamic enviroment.

im sure that some of out motor gurus will see this and chip in.....ill get some links for you to read, this subject has been discussed many many times on the forum.

if you do decide to build this.....we will help you on any thing we can.

 

[Bondo]

Re: Bulding new Boat called bolt -- need help

okay so this summer I am going to try out a boat design.

I am going to take a car or large marine engine and put it inside a 21' or 18' seadoo challenger and mount it in the center (you know the spot where they want you to store skis and stuff)

I am planning to use a large engine like a 6 or 8 cylinder corvette/mustang engine and marinize it with a new alternator/starter/ect.

anyways - so I need to know what additional work needs to be done.

on another note I am going to use a manual transmission to shift gears while underway (I know there is a large debate about this but I think that with enough speed and HP you could shift gears. it would go ilke this
•Start in gear 1 (probably gear 3/4 on a car) and accelerate to crazy plane
•To save fuel economy and lesson RPS shift to 4th/5th gear
•To achieve maximum fuel economy and speed shift to 5th/6th gear

I can drive stick and shift gears fast.

So i need people to help me learn how to mount the engine - and to choose a different pitch impeller (if that is possible) to achieve maximum fuel economy and save RPMS -

If anybody has done something like this before let me know

additionally could I use an automatic transmission for future builds (I have heard that some bearings could possibly break- is there one that won't for marine use - will it switch gears underway) - what about semi-automatic/paddle shifters.

also if i go really fast will I need front ballast tanks to keep the boat from "flying"?

Ayuh,.... Welcome Aboard Computerwhiz2,....
Ya better stick to 'puters,... yer outa yer league in boat design....
A standard shift transmission will Not work....
An automatic has been tried, 'n was a dismal failure...

Stuffin' a V8 into yer barge will be quite a feat, 'n yer pump will need to be Replaced with a larger 1, as yer seadoo pump won't be able to handle the loads, even with a different impeller...

oh,... no need for ballast,... That huge hunk of Detroit iron will hold it down...