Homemade hydrofoil?

[sloopy]

Re: Homemade hydrofoil?

Davis makes the the best foil we all know that. Searays also is foil shaped.

 

[sloopy]

Re: Homemade hydrofoil?

ALSO! Every flat one I look at online does not mention the word FOIL only the the ones with a foil are called a hydrofoil.

 

[MajBach]

Re: Homemade hydrofoil?

HINTS THE NAME HYDROFOIL!

It's called marketing and you just proved that it works!<br /><br />Hydrofoil: noun<br />A device consisting of a flat or curved piece (as a metal plate) so that its surface reacts to the water it is passing through

 

[sloopy]

Re: Homemade hydrofoil?

Webster's : HYDROFOIL: A boat that has fins attached to the bottom by struts for lifting the hull clear of the water to allow faster speeds. <br /><br />And I looked again all products with the name foil have the airplane wing shape. All products made out of aluminum or have a flat surfave on both sides, DO NOT SAY FOIL! But on both cases, the description says they will do the same thing (Better hole shot, faster, smoother, bowdown ect..)

 

[Boomyal]

Re: Homemade hydrofoil?

Sloopy says that "Davis" makes the best hydrofoil. Can you supply any additional info or website on that unit. I'm making a list of lifting devices (including four blade propellers) so that I can study the claims and characteristics of each to determine what will best deal with the minor handling issues of my light 20' runabout w/o adjustable trim.<br /><br />Also, Hopsdak, if you know of any sites for the Nedski, I would appreciate you listing it.

 

[airman]

Re: Homemade hydrofoil?

Majbach, I'm really not looking for a fight here, I like most of your comments. I just wanted to point out that hydrodynamics and aerodynamics are very similar at subsonic (ie boat) speeds. A wing moving thru the air sees the air as an incompressible fluid and that's how the air behaves until you get towards the sound barrier. At least thats what every book I had to read in school said. It is worth noting that the people who study aerodynamics still can't figure out how a bumblebee flies. It's also worth noting that a plate doesn't need to be curved on top and flat on the bottom to generate lift. Millions of paper airplanes have been built with flat wings. You can even make it curved on the bottom and flat on top and it will generate lift. I flew my little trainer R/C plane upside down lots and it did just fine. So, to the point of the original post, as long as you've got a good piece of aluminum it should work fine. Who gave the "pro" his credentials anyways? The picture you posted looks like someone with a nice home shop trying to make a few bucks aff a simple project. If you want to put the bend on the end and you don't have a brake, the edge of a good strong table and a ball pein hammer will do an acceptable job.

 

[MajBach]

Re: Homemade hydrofoil?

Airman: I don't read your reply as provocative. I must have misspoke or you misunderstood because I agree with most of you said. I do not however agree with the incompressable fluid. Even pitot tubes have a compressabilty factor that must be taken into account at slow speeds. I'm sure you've seen the wing tip vortices and the 'mist' that occurs above a wing at high angles of attack due to the air becoming low pressure. <br />Something for you to consider, why are boat props and airplane props so different? One works on Bernouli's (sp?) principle while the other does not.<br />Don't know if my credentials of are any signifgance but I have been a commercial pilot since 1987. Still can't fly RC's though.

 

[walleyehed]

Re: Homemade hydrofoil?

The most dangerous combination........Pilot with tools.........

 

[airman]

Re: Homemade hydrofoil?

Pilots with tools? No problem! Make lots of work for the mechanics! Actually they're pretty good generally. Nothing like putting your own a** on the line to make you check twice. Not that I haven't seen some really scary stuff on homebuilts though. As to the prop issue, I haven't studied it much but I've always felt it was mostly due to the higher density of water. BTW I was told of some really radical new prop designs being worked on for tankers and the like. Big scimitar shaped things, much like the unducted fans that were being studied a few years ago.

 

[MajBach]

Re: Homemade hydrofoil?

The most dangerous combination........Pilot with tools.........

We may be more resourceful than you think. I can remember one day many years ago on a lake just big enough to be called a puddle 50 miles north of nowhere. The plane started listing seconds after striking a deadhead with my starboard float during landing. I managed to 'Macgyver' together a couple of patches, one for each breached bulkhead, out of cedar pitch, wood bark chips, chewing gum and one pair of underwear. Me without my tools......

 

[Chinewalker]

Re: Homemade hydrofoil?

Back to the original point - Oz has a 150hp on a 16-foot boat! That boat ought to literally jump onto plane as it is - what exactly are you trying to gain by adding a foil? As it is (whether realized or not), you're running a high-performance rig and you should be running quite high on the transom - high enough that the propeller is running a fair amount out of the water. You shoud also be running a low water pickup. If you're looking for better performance in a 150hp/16-foot set-up, you'd be better served spending the money on some prop work, transom jack, set-back plates, etc...<br />- Scott

 

[ZmOz]

Re: Homemade hydrofoil?

It does plain rather well as it is, the reason I want one is to be able to plain at much lower speeds...and save gas. I've asked on another forum about jacking the motor up, and after a very long thread the general thought was that it wouldn't do much for my particular boat.

 

[vidar]

Re: Homemade hydrofoil?

i think it woud be a better idea to add speed rails to the strakes that generates a good lift..less water escapes to side of boat..and "holds" better in turns...more lift :better milage..

 

[ZmOz]

Re: Homemade hydrofoil?

Care to elaborate on that?

 

[Dhadley]

Re: Homemade hydrofoil?

You mean the speed rails made by Volvo Penta?

 

[vidar]

Re: Homemade hydrofoil?

it is several makers...but designed so the water dont slip of rails so easy...kind of L-shaped...one side of L horisontal and other pointing down...

 

[vidar]

Re: Homemade hydrofoil?

this may give an idea... web page

 

[catfish1]

Re: Homemade hydrofoil?

interesting no wax! but that wont allow his boat to plane at lower speeds.

 

[vidar]

Re: Homemade hydrofoil?

the more you keep water under boat hull the lower speed you need to plane.....length and weight also plays a role here..if the boat is wery heavy in rear it is clearly a benefit w/foil...but i dont think the milage is best when driving at that speed because the boat sits a bit heavy in the water...and causing more drag.... and every thing we put in the water gives more drag.... but every setup is a bit different..so why not make one and try?

 

[catfish1]

Re: Homemade hydrofoil?

i say buy some smart tabs and be done with it! tabs will offer the slowest planeing speed you can get.... if you want to make a foil, make a foil! it will work to some degree!