Wednesday, March 20, 2013

Elecrtic Motors

My electric motors are mounted!   This is the Minn Kota Riptide 160 EM that mounts on the engine.  Together the two motors are 160 lbs thrust.  They have separate wiring and control, so one could keep running even if one breaks.  I like to have options when things fail.

Monday, March 18, 2013

Paravane 2 - thinned down

I made the center body only 4 inches wide instead of 1 foot wide.  This makes the paravane lighter.   It seems to work well.  Tested early in the morning before school and the sun was bouncing off the water into the camera.  So the quality of the video is bad even though the results are good.  :-)

Friday, March 15, 2013

Becoming a hydrofoil expert

I got the book "Hydrofoils design build fly" by Ray Vellinga in the mail today.  It looks like a very good book.  I should be able to learn enough to make paravanes that work well.

There are human powered hydrofoils.  A human is about 1/8th Hp and with the machine is over 200 lbs.   My solar powered boat wants like 25 normal  to 100 lbs peak pull.  So this should be less than 1/16th Hp each, but I have 2 paravanes, so less than 1/8th Hp.  The electric motor I have is about 3.5 Hp.  The drag for the paravanes should be acceptable, if I get a good design.

Thursday, March 14, 2013

Video of Paravane 2 experiments

Here are some videos of Paravane 2 after it was balanced by cutting out part of the front of the 2 keels. 

We had some trouble with seaweed:

More trouble with seaweed

Nice run:

Another nice run:

Using 3 lines to control angle better:

Using 3 lines again:

Just 2 lines, front and back, not bottom of keel.  This can flip if I pull to hard.  Catamarans have two stable positions and one is not good.   Thinking about a monohull design.

The keels are trying to push up on the water a bit but the water off the far keel pushes on the bottom of the main body and lifts it up.  I will probably try cutting down on the width of the center piece next.

Thursday, March 7, 2013

Results for Paravane 2

The front was too heavy and it would make like a submarine.   While in submarine mode I could pull about 40 lbs worth.   We then put a rock on the back so the front went up and then it would plane.  Then we were around 20 lbs force on the string.   My son wants to edit the video and we don't have pictures of the action.   The dock had a boat in the middle so we were running up and down the beach.  Sand flies were bothering the boys so experiments were cut short.   We will try again.

Next time we should bring GPS to get an idea of how fast were are going.

Also more than one camera could be good.  One doing stills and one doing video.

Even with some coconuts it is still nose heavy:

 Tried some small coconut halves for balance.

But still a bit nose heavy:

 Then added some rocks and it was reasonable:

Starting to move and the angle is good:

Every wave tank should have palm trees:

Wednesday, March 6, 2013


One thing a computer guy living on a tropical island has to worry about is redundancy and backups.  There is no Fry's in Anguilla.  Anything you order takes at least a week to come.  When I think about boating I do so with a keen eye to redundancy.  Some of the things we will have are:

  1. Solar/Battery/Electric  - Even if the battery goes dead we can just wait a bit to charge it up.
  2. Outboard - Eric got the 50 Hp outboard engine working.  It was not as bad as I had feared.  This can move me along like 12 knots for 50 miles or so on the two 6 gallon tanks I have.
  3. Sail power - this is a sailboat so wind is an option
  4. Kite - I have a few kites.  I think even a small kite could be fun for steering with rudders and engine up.  If I stand near the front of the boat it will turn downwind, if I stand near the bank the back will go downwind.   Will have to try this just because.
  5. Sea Anchor  - can stop out in the ocean anywhere and take a break
  6. Regular anchor - most of where I go will be shallow water
  7. I have spare rudder and daggerboard.
  8. Initial testing will be done upwind so we could drift back to the harbor if we had too.   
  9. We will also have cell phones and these work further from shore than we will be going for some time.
  10. Installing a VHF radio
  11. We won't be going out unless the weather looks good
  12. The boat has so much foam built into it that it can not sink.
 So we should have lots of redundancy.   

Paravane prototype number 2 is almost ready

I got my aluminum paravane back from the welder today.  I cut some styrofoam to go on it and took some pictures.  I was planning to put the fiberglass and resin but I have a sun cure resin and it was cloudy.  If we get any sun tomorrow I will finish this and try to test it.

With the foam resting on top, this is the view from the front.  It is sort of a toy catamaran with huge keels and no mast.  At slow speeds the foam will also act like a keel.   The string attaches on the right, so I want that one to lift out first if the pull gets to be too high.  This should reduce the pull even though the left keel was still in:

This is the view from the side.  If you look close you can see where the string will attach.  The foam has been cut away a bit:

This a view looking down the way the string will be.  Note how it attaches at the top of the close keel and is in line with the bottom of the far keel.  I think this will reduce the rolling force from the string.

This is a view with the foam set to the side:

I need to be able to lift it out of the water while I am in the boat, without hitting the boat.  I have a pole with a hook on it that I use to grab the mooring for the boat and expect to use that.   The welder made this nice handle but if there is water going over the top it will cause drag, so i might cut it off.  I was thinking to have an aluminum welding rod between the inside of the front tabs and have drilled holes there in case I decide to put a wire there.

The goal for this paravane prototype is to test the stability of this basic design at slow and higher speeds and to get more pull on the line than the 6 lbs we got from the toy sailboat prototype.