Help designing a submerged ball to guide my wife lake-swimming

This is the perfect crew to ask this: I need help designing an underwater ball I can tow behind a kayak or SUP or canoe. My wife needs to swim with a snorkel because of neck mobility issues, but she is like a barracuda when she gets going! In the summer, my son and I go to local ponds and lakes for him to train for triathlons: there are submerged trees and branches and rocks and I guide him away from them. But with my wife, she could not see me at all, even if I paddled right beside her.


her field of vision is somewhere between 90 degrees straight down, and about 30 to 45 degrees down from the surface.
But she asked if I could tow a “ball” behind the canoe, one that would sink, but not be too heavy.
Any ideas from the think tank? I’m going out to test things today like a bottle of water, or with some pennies in it. I wonder if there is some material that is just a little denser than water that could be about dodge-ball size?
thankee!

What about using one of those styrofoam belly boards and suspending a waterproof PFD light from it. A lot less drag.

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Cool idea! Do you know of a pfd light that would sink (I realize, this is probably the exact opposite of what people normally shop for in pfd/canoe safety devices :stuck_out_tongue:)

Not specifically, but most PFD lights are pretty compact and are not designed to float. You could always add a bit of weight if necessary. I thought of a PFD light rather than a dive light because a PFD light generally has 180° coverage instead of just shining forward.

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How about one of those swim toy torpedos that you throw underwater. We used one with our kids, they went quite far, so little drag. they come in a variety of colors and are not that expensive, cheaper than this example I have linked.

Amazon.com: Torpedo Strike SpinFin 10.25" Large Ultra Premium Pool Torpedo Rocket Spins & Glides Up to 30 Feet Like Underwater Football for Under Water Passing Games Underwater Torpedo Diving Toy Glider (Pink) : Toys & Games

they are designed to sink, but not go straight down, so attached to a tether they could work quite well, and if a bright color you might not need electronics, like lights. Or you could probably attach a light to it if needed.

You might need a swivel on the tether, I forget how much they twisted as they coasted.

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Does your wife use a snorkeling snorkel or a swim snorkel? I wasn’t a “swim team kid” and didn’t even know about the latter until I saw the video of Katie Ledecky using one while swimming a length of the pool with a glass of chocolate milk balanced on her head. She didn’t spill a drop, of course. :rofl: I now use a snorkel because my technique is terrible and haven’t mastered breathing to the side. Let us know if you come up with a solution. TY

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!!! Katie Ledecky swims faster than me even with a glass of chocolate milk on her head! Gotta show this to my wife…

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I was going to suggest the same toy - this link is for one that is designed not to spin. The fins are straight and it has less drag:
Amazon.com: Torpedo Strike DartFin 11.25" Pro Size Ultra Premium Pool Torpedo Rocket Glides Up to 40 Feet Like Underwater Football for Underwater Passing Games Underwater Torpedo Large Diving Toy Glider (Yellow) : Toys & Games

My brother made a version of this back in the 60s. He used a wooden baseball bat as the hull of a model attack submarine about a foot long, with fins and a conning tower, weighted at the keel to be just slightly buoyant. It could travel all the way across a pool submerged, then would slowly surface as it slowed down. It hurt like hell if it ‘accidentally’ caught you in the back, wonder how that happened…

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Prototype 60’s toy! Dive dive dive!