newbie help plz....building a off the wall boat(s)

[TatTude]

Hello, I am getting into this boat building thing just like the rest of you. However mine is on 2 different levels of boats.....The first level is it will be R/C (Radio Controlled) and the second one is that it will be a min. of 13' long and 4-6 feet wide and will be of the offshore racing class mainly the Cigarette style.

Now with that crazy statement made how do I get started? I know how to work with wood to some point mainly balsa and lite plywoods.....as well as fiberglass and most kinds of epoxys....my main questions are how do design and start building the hull? It must be a Deep V class just like this Cigarette boat in this pic.

http://i116.photobucket.com/albums/o14/Tattude/451.jpg

As for powering this monster I would like get started on the hull before desiding on what engines will go in it. I am thinking about either one big lawnmower engine that would be turbocharged or 2 smaller R/C 150cc aircraft engines.

Thanks for looking
John

[longliner45]

there are experts in this field ,,on this site ,,luky day for you,,,,,doug lord,is one,,,,,good luck ,sounds like fun,longliner

[TatTude]

Thanks for the info! Hopefully he will chime in!?!?!?!:confused: :) If I can get what I want all worked out then I want to start selling these.....Also I would make bigger ones a person can ride in.

[timgoz]

PM Doug if he does not "chime in".

Welcome.

Tim

[TatTude]

His PMs seem to be turned off so I sent him an email....I really need to get started on these projects...I have 7 customers wanting to make pre orders...anyone that can help would be HUGE!!!!!!

[longliner45]

doug is trying to contact you ,,you have no pm adress,,,look up doug lord ,,longliner

[alan white]

You might get 25 hp into 13 ft. A suggestion would be a 250cc motorcycle engine, single or twin. This would give you a clutch and ratios to choose from. A water-cooled 250 would be icing on the cake.

Alan

[TatTude]

doug is trying to contact you ,,you have no pm adress,,,look up doug lord ,,longliner


Please give doug my email ssosaleen@Yahoo.com....for some reason i cant see his PMs?

[longliner45]

he tried ,,and was told ,,email malfunction,,,,why dont you have pm capabilitys?

[the1much]

have you got a scaled design yet? or building as you go

[Doug Lord]

Geez! I looked in every forum but this one;thanks to Longliner for trying to help. Based on what I've read(13' scaled down offshore type powerboat-radio controlled) I would strongly urge you to not pursue such a large rc boat unless you're going to sell it to law enforcement. You would need a spectacularly costly radio system to begin to make it safe. The R & D costs to properly work this kind of system out would be very high in both dollars and time. If you insist on pursuing this idea I hope you would involve an independent marine test lab like Imanna to help you get it right.
What is your idea of how these things would be used? And to whom would they be marketed?
You can contact me at: lorsail@webtv.net or here now that I've found it. whew!

[TatTude]

Geez! I looked in every forum but this one;thanks to Longliner for trying to help. Based on what I've read(13' scaled down offshore type powerboat-radio controlled) I would strongly urge you to not pursue such a large rc boat unless you're going to sell it to law enforcement. You would need a spectacularly costly radio system to begin to make it safe. The R & D costs to properly work this kind of system out would be very high in both dollars and time. If you insist on pursuing this idea I hope you would involve an independent marine test lab like Imanna to help you get it right.
What is your idea of how these things would be used? And to whom would they be marketed?
You can contact me at: lorsail@webtv.net or here now that I've found it. whew!


Hello Doug! great to hear from you!!! Though I dont know why you cant send me an email? Anywho, a little history about me....I have been in the R/C business and hobby for more then 20 years....give or take a year or two. lol There is really alot of high tech parts and engines in the hobby that could power something like this but maybe a little smaller? Though I do agree that a motorcycle engine would probably be best for power and what not for this size of boat....anyway I also fly model airplanes that are up to 50% of the full scale size that use 150 to 363cc gas engines....So i really think that the technology is there to support something of this size. I am just a total n00bie to designing a boat! But I also know when to say when and if something of this size is not something that can be done then I would still like to do this style just alittle smaller is fine too.....You had also asked where I would run something like this? well there is a couple big lakes around me that I can run a boat of this size and not have any problems...they have some small R/C hydro races there every year...


thanks John

[Rick Willoughby]

We have a version here in Australia of what you describe that you can sit on - it is called a JetsSki. I expect you have them in the US as well. Just joking.

However a jet ski might be a good place to start. The hulls are proven and the drives are made to work in water. I would certainly consider an enclosed prop for something of this scale that could get out of control. Marinising a motorbike engine driving a prop brings in a lot of issues.

So a suggestion is to start with a jetski hull to produce a mould. You could lengthen is if you did not like the proportions. Then build a nice low deck.

If you want to start drawing up you own hull then download the free version of Delftship and learn how to use it. You should be able to model a power boat accurately by looking at various pictures. You could post your design here for critique but they are not difficult to shape. Detail of the design will depend on how you set up the engine. Forces a larger than in aeroplanes so you need stronger mounting points - a good reason to study a jetski first.

The things with the boat is a "V" hull possibly with a triangular flat planing section and planing strakes. Keep the weight low in the hull. Make sure it has ample solid buoyancy to stay afloat if it crashes and gets holed.

Rick W.

[TatTude]

We have a version here in Australia of what you describe that you can sit on - it is called a JetsSki. I expect you have them in the US as well. Just joking.

However a jet ski might be a good place to start. The hulls are proven and the drives are made to work in water. I would certainly consider an enclosed prop for something of this scale that could get out of control. Marinising a motorbike engine driving a prop brings in a lot of issues.

So a suggestion is to start with a jetski hull to produce a mould. You could lengthen is if you did not like the proportions. Then build a nice low deck.

If you want to start drawing up you own hull then download the free version of Delftship and learn how to use it. You should be able to model a power boat accurately by looking at various pictures. You could post your design here for critique but they are not difficult to shape. Detail of the design will depend on how you set up the engine. Forces a larger than in aeroplanes so you need stronger mounting points - a good reason to study a jetski first.

The things with the boat is a "V" hull possibly with a triangular flat planing section and planing strakes. Keep the weight low in the hull. Make sure it has ample solid buoyancy to stay afloat if it crashes and gets holed.

Rick W.

Hello Rick, How you have come with some good points! However I must say I like the jetski engine idea!!! However I do have some questions on how one of those engines works? where and how does it get the water to the engine if there is no holes in front of the engine in the hull ? I tryed looking for some vids on youtube and other info pics but really havent found much yet??? Im looking forward to hearing your thoughts and others on this idea.

Thanks John

[TatTude]

Now I did find this and this is just badass!

http://www.youtube.com/watch?v=p9ryf-Uam0g

[Rick Willoughby]

John
This is more my style of boat:
http://www.youtube.com/watch?v=l2UOH65QOI4

I think Hamilton jets were the first jets. Here is some detail on operation:
http://www.hamjet.co.nz/index.cfm/The_Hamilton_Waterjet/How_a_Waterjet_Works.html
Basically it is an axial flow water pump or you could consider it an enclosed propeller. Very little chance of damage to the prop unless you operate in really trashy conditions. The axial flow bit is important from an efficiency perspective.

The thing about a jet boat is that they turn very quickly because the hull does not grip the water like a boat with an external prop and strut:
http://www.youtube.com/watch?v=pbN4tvQD3Jk

This might be a good place to start looking for bits:
http://www.sbtontheweb.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=P40
I suggest you get something tried and proven first. You are probably best picking up a second hand jetski and then looking for refurbished parts to suit the number you eventually make.

The jetski units are really neat compared to fiddling with a motorbike or mower engine. If you wanted to go a smaller scale then you could fiddle with a drive unit of your own manufacture but jetski size is serious power in a very compact form.

Rick W.

[Workinforwood]

I don't exactly know anything, but I do have a jet ski and the water sucks in to cool the engine right in front of the prop. There is a grate under the boat, the water goes up through the grate and the driveshaft and prop is in there which slams the water out a hole in the back where a tube directs the water direction. The coolant pipe is right in front of the prop on mine, and I don't know how it possibly sucks water in that tube at that location as it seems in my mind to be impossible, but it does it nonetheless. I have to climb under and inspect the grates periodically because the suction is powerfull and the grates can get clogged with weeds, in which case you loose speed and cooling abilities. It's safer than an open prop, but can still kill you. A lifejacket strap can get sucked up and wrap the shaft for instance and then you'd drown. I had a rope from a tube get sucked up and wind the shaft, then had to get a tow and pull the whole shaft out to unwrap it. But that's all off the topic...but that is where the cooling tube is.

Oh...motorbike motor, flip it over in water and you are done for. Jet ski motor has safety valves, so if motor is upside down, valves close, no water enters motor. You do have to re-flip the motor in the proper direction so the valves don't open up when the motor is only halfway back to normal position. Also, motorbike motor might be more prone to cracking the head if submerged due to hot engine being cooled super fast. Less likely on a jet ski, but still it does sometimes happen on jet-ski motors too. There was a guy up in town last year with a jet ski he was selling where he modified it to have a seat inside the hull with a regular steering wheel and an outboard motor off the back. I think he was using it for racing, but who knows.

Good luck with your project. Let me know when you test it so I'm not in the water or withing 500' of shore ! lol