Picklefork hydroplane

i am wanting to build a picklefork hydroplane seen here http://www.glen-l.com/designs/outboard/picklefork.html

my question is can i scale up the plans to make the boat 12-14 feet in length (im not saying just make it longer im saying make the whole boat bigger. I dont see a problem with it just making sure.

also i have a 650cc (50hp) 1992 yamaha jetski. does anyone see a problem with using this as the propulsion system? wont have reverse but thats not a big deal

 

scaling the boat up dimensionally would work just fine for the hull lines and shape. the real problem here I think is the larger the hull than the larger the forces. Larger motor, larger hull, forces on the hull go up exponentially. so you have to up size all the primary structure, or get some engineering help on the size and strength of the structure.

One thing that might be a "poor mans" way to beef up the structure is to find a similar type of boat plans of the size you like, and "borrow" the structural design and use the lines and shape of the hull of the scaled up smaller boat.

If you just make everything bigger you could end up with a very heavy hull, or one that is not strong enough. Or get some professional help on the redesign of the primary structural elements at the least.

Good luck.

 

'scaling' performance boat designs

f3rr3t - if you are making small changes to the size of the boat, then you probably won't get into much trouble, but generally, direct scaling of performance hull designs such as 3-pt hydroplanes is not the best approach. Lift, drag and stability forces change rather dramatically and these designs are very sensitive to weight and power. You are best to make the changes to your preferred design in a way that you know will balance the required lift generated, hull & payload weights and power expectations.

 

do you know of any 12-16 foot 3pt hydroplane designs? i have searched but no luck.

i plan to build a cedar strip canoe first then a 3pt hydroplane for myself then my uncle wants to build a 16ft tunnel king over the summer

 

there are some tried and true hydroplane designs around. most are fairly dated designs, but are a good example of structural construction of these hulls.

try clark's ben hur or inboard hydro

or at svensons cabover or sportshydro

or here is a 3-pt hydro

you might consider a tunnel hull design. there are some good examples of tunnels around...these are dated designs too, but as with the hydros, show the construction methods pretty well.

all of those designs can benefit from some improvement design features to bring them from the 60's-70's design arrangements.

 

I would be concerned that using a jet ski propulsion package might not work with a "three point" design. That is, you may be trying to put the jet inlet in an area where the inlet could injest air and that might make a mess of things. With a pickel fork type of boat there isn't supposed to be much (if any) of the aft part of the hull in the water. It is supposed to be lifted by the aerodynamic forces under the hull, the sponsons in the front, and some prop lift at the back. If you had all of that transom width in the water back there, you would have a lot of drag to go along with it...

Also, using a jet ski system might push your CG way forward, assuming you are going to put the driver ahead of the engine. Which would put too much load on the sponsons and the boat won't go very fast. A more conventional old school round nose type of hydro would be better than a pickel fork design in that case.

You might be better off with a monohull (or some type of deep V hull) in that with a monohull you would for sure have the inlet in the water so long as it is back near the back of the boat.

A deep V hull, with the waterjet inlet at the very back, with the driver located near the back to get the cg right might be a better way to go. Maybe the 13' C-D runabout (designed for about 50 hp) from Glenn L, or if a deep V makes sense, think about Dyno Mite, or if you want a one place padded deep V, look at plans that Dillon sells at

http://www.dillon-racing.com/

As a starting point. If you are thinking padded V you need to buy Jimboats book and learn all you can about the effects of CG and balance on these hulls you you could end up building something that won't work at all.

I think a boat like a Dillon with a jetski drive in it might be a lot of fun.

 

Bob Dillon has done some good homework in the tunnel hulls and the vee hull that he has built. he's also got some good connections & links on his website.

also, the tunnel king is a good example of a tried and true tunnel hull design. you'll enjoy building this one. good idea to update the design to current, though.

 

wow all of you have been extremely helpful.

my first project is going to be the 16ft stripper canoe https://www.boatdesigns.com/products.asp?dept=189

once that is finished i will build the X1 hydroplane seen here http://sandypointboatworks.com/X1hydro.html but modify the nose as seen here http://i158.photobucket.com/albums/t94/mattspidermanking/19.jpg now can i use a jet ski motor with a shaft connected to a prop?

then after thats done me and my uncle will take on the project of his boat https://www.boatdesigns.com/products.asp?dept=343 he has a nice 150 mercury jet drive outboard for it or a tunnel king he hasnt decided

 

Sounds like you have a lot of ambitious plans, after all that if you are still in a building mood, yes you could use a jet ski motor and have it drive a prop, but that will generally require some machine work and the cost of that my be prohibitive for a one off. Depends on your mechanical and machine shop skills, and how much you do yourself. Sometimes you can end up spending a lot of money to save a few bucks.... An outboard might be less expensive in the long run and would be a lot less work, but to each his own...

Whatever floats your boat....

 

i was just trying to use motor i had here. i have a lead on a 2001 75hp mercury that would be nice.

 

here is a site that has vintage wood boat plans for free down load. Click on the hydroplane link. lots of good stuff to get you started.

http://vintageboatplans.com/