It might not be a bad idea to have a lightening (rod) arrestor on a boat, but not to make sure the lightening hits the metal lightening rod instead of the boat ( a common mis-nomer). That's not how lightning rods work. Lightening rods give the static electricity an easier path for the static aura to dissipate, making the highest point (where the lightening rod is, less desirable for the lightening to strike, so hopefully the lightning will strike something else close by (like the house or tree next door). At least that's my understanding of how lightning rods work. I used to be into Ham radio, and built several antenna towers. We would run 1/8 inch bare aluminum wire up the antenna up to a lightning rod mounted near the far top. What this did was help dissipate the static (the blue aura, that (makes your hair stand up, and faint sparks coming off your arms and hands occurs just before the lightning strikes ( yes I have been struck by lightning).
So basically if lightning was going to strike within 30 feet of your boat, if you have a mast with no arrestor, the lightning will surely hit the mast (easiest path). If the mast is arrested, then it becomes a less likely target because the static aura around the antenna top was able to dissipate enough to make it less likely to strike the highest point, that's why the lightning struck the water near the oil derrick, because they likely had arrestors in place making it not so much a bulls eye.
All this stuff about Ben Franklin and his inventions (the key on a kite, and the lightning rod) and how they work I thought was something we all had to learn in grade school.
One of the times I did get struck there were 6 of us under a tree at a golf course. I felt the aura and could see my hair standing up and the small sparks emitting from my hair and fingertips, I yelled hit the dirt, and all of us dove down on the ground (making us less attractive), the lightning did strike the tree, we were all slightly injured (mostly just shock and a couple minor burns), but all of us survived.
If it were me and I was caught out in a thunderstorm on my TI, If I could I would take down the mast I would then hunker down in one of the seats as low as possible. I sometimes carry one of those metalized space blankets on board for emergencies (hypothermia), I would cover myself with that making sure one corner was in the water so the static can dissipate from the blanket making me a less likely target (like a lightning arrestor or faraday cage). Of course if the main bolt of lightning strikes you directly you are toast (luck of the draw), but if it hits somewhere else on or near the boat, yes you will likely get some secondary injury, and mostly likely be unconscious for a bit ( I was). But at least you are still in the boat with a much less likelihood of drowning, and/or being eaten by sharks. Plus the space blanket helps you stay warm and dry (er).
BTW, that's nonsense about the VHF radio, and the cell phone, I would still turn them off though. The reason being if they are off when the lightning strikes, they may still work when you turn them back on again after being struck (on the unlikely chance your still alive and need help).