Tracking a sunken model

Does anyone have any bright idea’s or gizmo’s to assist in locating sunk models ?

After a recent sinking of my yacht Ive been doing some thinking about a self deploying float with line attached that will reel out when the yacht sinks, so that it can be easily retrieved.

I am currently working on a float with a reel attached that will carry about 50 metres of line strong enough to haul up a model yacht from down under, I am using line with about 80lb breaking strain 'cos its thin and I feel this should do the trick.

The only thing I haven’t worked out yet is how to attach the assembly to the yacht where it can deploy when sunk, but not in a gust of wind that tips the yacht temporarily on its side while blowing wind vertically along the mast.

The other problem is that if it is deck mounted we get the same issues when the yacht submerses downwind overpowered.

Any suggestions ?

The best thing to do is to test the boat in a pool and get any leaks before going to the lake. Or stay close in the shallows.

But I have seen many different kinds of gizmos including a film can with an Alka-Seltzer on top that dissolves and releases a float & line!

The cleverest idea I have read, is a devise that is attached to the boat via a sweet (candy) that would disolve after a period fully immersed.
Upon release, the devise with line attached, floats to the surface and you can haul the boat up.:cool:

Hard candy dissolves slowly in water, so it would have to be some kind of thin sugar string or candy. I preferred the seltsa tablet, because it dissolves quickly. A very light line on the float would be ideal, attached to a heavier line that you can pull up via the light one. This all is bulky and requires room. The other problem would be where to put the whole thing, because the float or the line could get caught in the rigging on the way up.

Is 80 Lb. the right line? A typical 1meter weighs about or less than 10 Lbs., so you could probably get away with lighter line, unless the boat is caught in weeds or roots, and then the line would serve as a locator for a diver or gulp hook.

Here ya go.

Davis Marine Instruments - $6.99
… remove keys and attach longer line
… secure to top of mast

Problem = single use only, but wouldn’t you learn after the first time?


I’m kinda with TomoHawk, in that the boat should be tested so as not to take on water. I’ve had boats that leak but until I find the hole(s), I check it, empty it, and relaunch. How did your boat sink? I realize you ran this post with a “rescue” idea yet maybe your efforts are misdirected… but I certainly understand the need to tinker.

And, just out of curiosity, how many sailors here have had a yacht sink?
Me = 0


Before you put in the radio for the last time, check the hull & deck joint by putting some water in the boat ( bout 1/3 - 1/2 full) and roll it around, looking for drips at the deck joint, keelbox, rudder.

If you’ve got no leaks then, you’re pretty much OK.

By testing in a tub or pool, you can also check how it’s balanced; on the water line, and not listing.

I am thinking some device similar to the inflating lift vests inside of the boat. Of course you would have to make sure it wasn’t to strong that it would explode your boat.

(just a thought)

Velly Intelestink…

How would you get it to inflate, or how would you get the inflators to activate the thing to fill up?

I keep thinking of Seltzer tablets, because they fizz with CO2, and you could fill the whole boat with CO2, if it was air tight (which was the problem in the first place!)

The powerboat guys will just tell you that it’s your fault because you didn’t fill the hull with bouyant foam. OK, but how would you run the sheets, radio & pushrods?

You are kidding and it’s a retorical question - right ? :sly:

If you are serious, there is probably some suggested winter reading that might be in order, as many articles have been published about making a sailboat from solid foam, covering with cloth, rigging and then sailing. - process is probably the same way the “fly-guys” manage to fly a foam plane?

Powerboat guys like to fill every part of the boat with foam, so there’s no room for other stuff, adding several Lbs just from foam.

I like to have room for the winch arm, sheets, and your hands & arms.

Tomo —
I suppose you also need room for galley, head, nav table, and sleeping areas too ? :wink:

The idea doesn’t address “Diversion’s” current problem, but perhaps it’s an idea for any future off-shore escapades.

If you look at most 1 meter boats (as example) there is a lot of wasted room under the deck forward that isn’t used for anything except air. Ping Pong balls make good flotation - and I can assure you they don’t weigh 6 lbs. ! If you can keep any part of the hull/boat at surface level, you can eventually rescue it - but no - you probably can’t sail it to shore. You might want to take some solid 2 inch thick insulating foam, and see how much it takes to get to 6 lbs. My guess that much weight is significantly greater in size than any one meter boat. My F-48 weighs in at just about 2 lbs. - and that is 3 hulls of foam, 4 feet in length and two laminated veneer, wooden cross beams.

As for your desired need for under deck “room” - I guess that’s your call to make - space versus ability to easily (more or less) recover a swamped boat. The foam hull is just an option often overlooked - maybe because a solid foam boat with glass covering isn’t quite so high-tech as many would want. Doesn’t have the same ego appeal as carbon or Kevlar based composite hulls. :sly:

Isn’t it a lot easier to plan on ways to keep the thing floating at the surface instead of worrying about ways to recover it from the bottom using “selzer” tablets or similar ? Just curious.

Bill, I think you call the foam boats "surfboards. :smiley:
As for the galley, head & bunks, I’ll leave that to my motor cruiser: a 45-foot Bayliner ( sits on the shelf because it’s 1/15 scale!)

I bought some of that 2-inch foan to make a gas model hovercraft, and the whole 4x8 foot sheet probably weighs about 3 or 4 Lbs.

Another reason I don’t put in any floatation in my ODOM is that it doesn’t “need” any, I’m the only one that uses it ( in a “safe” environment,) and I don’t want to have to bother with rebalancing it (it’s perfectly balanced as it is!). But if I did my own 1-off, or something for kids to fool with, I would probably put some in.


Are you missing a decimal point here? I doubt very much that any model power boat carries 6# of foam. Dow blue foam weighs 2# per cubic foot, so 6# would displace over 187# of water. Man, that is one heavy model…:wink: Also, a big model with 3 cubic feet of foam.

By my calculations, a sheet this size should weigh over 10# if it is extruded polystyrene. Or are you saying that the above powerboats are filled with over 10 cubic feet of foam (2-4x8 sheets @3#=6#)? Time to do some fact checking Tomo.

Who cares what color the foam is. They jam it everywhere, and after the foam gets wet, it absorbs water and get even heavier.

I assume the ping-pong balls go in a bag to keep them together? You’d have to get the deck off to get it inside. Where would you be putting the ping-pong balls, and what would the displscement capacity of a ping-pong ball be (if you know )?

I would have thought that anyone in their right mind - even a power boat enthusiast - would have used a closed cell foam. This has a water take-up that is effectively zero. Any water uptake that does not involve driving air out of the foam is (by definition, unless the salinity or sometghing else changes during the experiment) neutrally bouyant: it cancels out of both sides of the equation.

‘If a body is immersed in a fluid, it looses weight. If that fluid be water, the weight lost is equal to the weight of water displaced’ (Archimedes of Syracuse). That’s why the ‘displacement capacity’ of the foam is inseperably related to the weight of the boat. Ever since around 250 BC, engineers throughout the world have generally found Archimedes principle to be a pretty reliable way of looking at things.

There again, was it the Indiana state legislature that attempted to make pi = 3 :diablo: ?


The yacht in question lost a stick on hatch and dissappeared in about 8 metres of fresh water in 10 seconds flat.

The divers took a week to find it due to visibility problems. The lake we sail in is an old clay quarry around 30 metres deep in the centre and any disturbance of the silt causes a cloud that cannot be seen through.

The deck hatch release problem is now being rectified with a new paint job to give it a better sticking surface, but I lost a servo and reciever as a result of time spent under water.

I think the floatation idea has merit though, rather than recovery from depth.

Cheers, Neil.

  1. We are using foam for buoyancy after a swamping. Closed cell will not absorb water, … and if it did, how much would be inside a boat when not sailing for it to absorb?

  2. For sake of discussion - just say a ping pong ball is 1 cubic inch - depending on boat size would provide the number of balls that fit. Don’t want to use ping-pong balls, then simply use an air filled bag fitted forward and under the deck. You can do the math - once you decide on area that can be filled. I suppose one could also substitute foam “peanut pellets” - or even bean bag filler.

The idea is to keep a sunken boat at or just below the surface. If whatever you use can do that, the mast/sail would probably be sticking out of the water.

Best idea is to make sure boat is water tight, and as Neil has mentioned - the tape around hatches sticks well. :wink:

Going from the slightly surreaal to the slightly surreal, I’ve been getting into glue-gun type hot glue rtecently for a variety of purposes.

Anyone thought of it for holding down deck opening covers: infinitely re-usable and sticks like you know what to a blanket. Just a warmer burner on a pencil gas torch andd… Yes, and keep it clear of the sails!

… and fingertips ! :scared:

for fun, I build cabinets and use hot glue for holding a lot of internal bracing until I can get out the pneumatic staple/brad nailer. Works great, keeps stuff from slipping during set-up, and allows part to be removed if something doesn’t quite line up correctly.

I suppose one could use a little “dab” to hold deck fittings until you rig for firt time - allowing for shifting of deck hardware slightly once rigged.