U/W dive plane video in the Abacos

[Travis McGee]

I recently spent a few months on my 48' steel cutter in the Abacos, based mostly out of Marsh Harbour. One of my friends flew in with a GoPro camera, and I was finally able to capture underwater video of some swimmers on dive planes. I've been refining this concept for a couple of decades now, but this is the first video of my "balanced dive planes" in action.

Put your YouTube settings to 720pHD, and wait for the under 5-minute video to load so that is runs smoothly.

The optimal towing speed is 3.5 to 4 knots. This is easily achieved with your autopilot. Typically we go dive planing when the wind is so light that we are ready to switch to the engine. It's best in warm, clear, calm water, so the Sea of Abaco was perfect, with its 12-15' average depths. Often we'll roll up the jib and go dive planing under main alone until everybody has spent a half hour or so in the water. It's a blast, the water rushing over your body must be experienced. Even at 4 knots, you get a "ground rush" when skimming over the bottom.

Matt Bracken / Travis McGee

https://www.youtube.com/watch?v=_h0d...ature=youtu.be

[Red Sky]

Very cool Matt.

[Travis McGee]

Anybody who ever sails in warm, clear water really needs one of these.

[Red Sky]

Sorry Travis, I should have included you in the thank you. Do your hands get tired leveraging the board? Would you have more control if the boards had two short handles with bike handlebar grips mounted at a right angle to the board instead of the holes?

[Travis McGee]

Originally Posted by Red Sky

Sorry Travis, I should have included you in the thank you. Do your hands get tired leveraging the board? Would you have more control if the boards had two short handles with bike handlebar grips mounted at a right angle to the board instead of the holes?

Your hands don't get tired, not for at least a half hour. On my latest version, the grip holes have "hand swells" on the finger/down side to make the total grip dimension about 1" in diameter. The ones in the video don't have grip swells, they are just 1/2" thick. This has not been a problem. Usually, other folks on the boat are wanting to get in the water before the diver in the water gets tired. Still, I think that grip swells will be an improvement for comfort, I just haven't had a chance to try a board with them yet.

We have tried versions with the grip holes far apart, but it's not an advantage. With the grips close together, you can hang on with one hand while clearing your mask etc. Some folks even use their index fingers to pinch their nose for clearing while diving. This is not possible with hand holes that are spread wider apart. There is no problem twisting, canting or rotating the board with grip holes that are close. On the board I used for filming, I attached the GoPro camera at a 45 degree angle on the right front corner. I could fly the board in all directions, while aiming the camera forward (board 45* to the left) or aim the board sideways at the other diver (board 45* to the right.) No problem.

I even made some boards with the hand grips on the edges of the board, cut in from the outside. This was a failed experiment, it's impossible then to hang onto the dive plane with one hand.

In the video, Doc is using his fins when he is rolling. He was new to dive planing, and the fin action is not needed. Watch how easily I flip inverted just by canting the board in relation to my shoulders. If you rotate the board compared to your shoulders, you become, in effect, a screw, and you turn, with no feet or leg action at all. This is accomplished with hand grip holes that are very close together.

[Cormorant]

Looks like a curious shark passed by at 2:40. Did they ever give you any trouble?

[Travis McGee]

Originally Posted by Cormorant

Looks like a curious shark passed by at 2:40. Did they ever give you any trouble?

Good eye! No, never had any problems. Usually I'm dive planing in mid-ocean when the wind drops and the seas are calm. 3.5 knots is the best speed, so we usually think about dive planing when we are thinking about motoring. Or if we are sailing at say, 5 knots under main and jib, we'll roll up the jib and drop our speed to about 3-4 knots on purpose. So it was actually unusual that we were dive planing in the shallow Sea of Abaco. Usually we are in the deep ocean, and it's extremely rare to see the random shark out there in nowhere. Anyway, I don't give them a lot of thought, whether scuba diving, snorkeling or whatever. Same applies here with dive planing. You just do it, and don't worry about what might be down there.

[minaret]

Originally Posted by Cormorant

Looks like a curious shark passed by at 2:40. Did they ever give you any trouble?

Maybe a big hook on the swimmer, just in case?

[HopCar]

The dive plane I have has the grip holes on the trailing edge and the pivot point is somewhat ahead of them.

It looks like your pivot point is between the hand grips. Does that make it easier to change the pitch?

[Travis McGee]

Originally Posted by HopCar

The dive plane I have has the grip holes on the trailing edge and the pivot point is somewhat ahead of them.

It looks like your pivot point is between the hand grips. Does that make it easier to change the pitch?

I've been making them and refining the concept for 25 years. The concept, distilled, is that the pulling point (the rope hole) should be about 45 to 48% of the way from the front of the board. The resisting point, the leading edge of the hand grips, should be about 52 to 55% of the way back from the front. This gives the dive plane almost perfect balance, like a balanced rudder on a speedboat or an airplane. The leading edge forward of the rope hole balances out the forces on the back of the board. It makes it very easy to steer up and down and in all angles just by twisting your wrists.

[Suijin]

Super awesome!

Any chance you would share a template of dimensions and cutouts? I'd make a couple of these in a heartbeat.

I'm surprised that you say you do this mostly mid-ocean...not as much to see as there is in skinny water, although the clarity of the water is it's own reward I suppose.

Thanks for the video, very inspiring.

[Travis McGee]

Originally Posted by Suijin

Super awesome!

Any chance you would share a template of dimensions and cutouts? I'd make a couple of these in a heartbeat.

I'm surprised that you say you do this mostly mid-ocean...not as much to see as there is in skinny water, although the clarity of the water is it's own reward I suppose.

Thanks for the video, very inspiring.

As far as a template, you can just make judgements from what you see on the video. I've made at least a dozen of them from bits of scrap ply from maybe 16" to 25" wide and 12" to 20" inches fore to aft. They all worked. Big guys need bigger boards than little kids. Making grip holes etc largely becomes a matter of taste and comfort. In the simplest form, it's no more than a sheet of 1/2 inch material with some holes cut in it.

Mid ocean on long transits in light air you look for things to do and even for ways to cool off. Lots of sailors hang onto their dive ladders etc and drag in the water. The dive plane just adds a new sport to a dull voyage. You can't see it much in the videos but you can do radical acrobatics, rolls, dives, combinations etc. While doing the video with two swimmers we had too many near collisions so what you see is rather tame, with each diver keeping to his or her own side.

A single dive plane in the middle means continuous rolls and S turns etc, to any depth your ears can handle on that day. We just couldn't catch it much on the video with two boards out. But in the deep ocean, you are very free, with no worries about hitting the bottom so you can do great arcing dives and returns. And the way the noon sun rays converges far below you is pretty amazing, so even with no bottom, it's very pretty.

Not to mention seeing your upside down boat through clear water while flying inverted just under the surface. It's actually harder to describe how to do all of this in words. Everybody that jumps in the water with a board figures it all out in about five minutes.

[FSMike]

I remember trimaran designer Arthur Piver writing about doing that in his book about sailing the original Lodestar tri from California to Australia back in the 50's IIRC. Looks like you've definitely refined the concept.
Good fun.

[Pelagic]

Great job Travis documenting the mechanics and joy of using a diving plane.

In the early 80's we used them a lot to survey new dive sites when running a 180ft liveaboard dive boat in Micronesia, exploring all that atolls between Ponphei and Palau.

Not to sensationalize but a caution on using them in high density shark locations.

Of course our interests were the reefs and finding lots of animals.

The sharks do react to the free diving signals of fluttering near the surface and we did get a number of close, aggressive passes that left us shaken.

We then switched to a scuba solution to be able to have more control.

Using a separate small signal line for giving (stop-start) speed , depth and course directions ...... We lashed compensating weights to the poly line near the plane's bridal to lower tow angle and it balanced out quite well.

Also because of added resistance from SCUBA gear we hooked on to the plane via crotch strap hooks to carry the load while steering with hands.

Once balanced and practiced... It worked well and we covered a lot of territory at about 50ft, without exciting the sharks.

Unfortunately, these days finding sharks in such numbers has become a rarity..... But this was how I found my first Silvertip at Orluk atoll in 1981.

[Flem.S.Coyle]

Looks like a lot of fun, Matt. I was hoping your exile to the Abacos was a working vacation, bent on the production of Dan Kilmer episode #2.

I'll have to order a couple of those dive boards, while waiting patiently for new dystopian fiction.

-Jeff