First off I'm not recommending anyone do what we do with our Tandem Island without major modifications to the boat itself. If you look at the CE plaque on the hull you see the boat is rated for two passengers 600 lbs total weight (passengers and gear). Also the CE rating on the boat is 'C' rating, making the boat not suitable or recommended for offshore use. In the US any boat more than 2 miles offshore is under the jurisdiction of the coast guard, and they have many strict rules about required safety gear, and emergency equipment. I have been stopped and checked more than once, if I did not have the required safety equipment ( ie... flares, PFD's, FM radios, etc). Go to the coast guard website for more info.
Here is the video:
[youtube]https://www.youtube.com/watch?v=2BcdE0137Xk&feature=youtu.be[/youtube] https://www.youtube.com/watch?v=2BcdE01 ... e=youtu.be
Here are couple extra pics showing the paracord lines, basically wrapped around the front AKA bar individually with cinch knots then thru the bottom of the tramp back to the back (I had to add eyelets for the line to pass thru). Each line then wraps around the 3/8 fiberglass rod at the back of the spray skirt, then around the rear bar, then just slipped over the stainless S hooks (from West marine $.85 cents ea). All in all I used about $5 bucks worth of 550 lbs test paracord (about 50 ft), and $9 bucks for the S hooks. Of course more expensive no-stretch line would work better, but with this I can easily walk around on the tramp now without fear of it breaking. There is no reason two adults couldn't sit on them now.
It takes me about the same amount to time to rig this as it does the regular tramp straps. If I need a little extra strength I can put a bungy underneath to pull the cords together, this also keeps the tramps more taught.
Here is a better view of the hiking stick slash dive flag holder (double duty).
Here is a closeup of the rope end that just pops over the steering knob (the whole works cost about a buck and five minutes to make)
Here is another handy feature that I didn't mention in the video. that little piece of spectra string wrapped around the gudgeon then looped around the bottom of the rudder pin, prevents the rudder from flying up into the air in the event of a rudder pin breakage, and you can still steer even with a broken rudder pin, at least until you get to safety. Of course the rudder flops back and forth and steering is much more difficult, but still steerable enough to get you home. A loop is not needed on the top side since all the steering and up down lines kind of help hold the rudder on at the top, it's only when the bottom joint breaks that the whole rudder flies into the air and becomes totally useless. Typically you can still struggle along with the top joint broken.
Hope this gives some ideas, everything I do is very simple, and have never made any mods to any of my TI's themselves, every mod I have simply bolts onto the stock boat. Quite a bit of the stuff is the original stuff I built for my first TI back in 2010, and just transfer it over to the new boats as I get them.
Off topic ... As divers we really have a lot of fun, and are serious about conservation of our reefs and the oceans. Here is another video of us diving in the aquarium at Disney world, pay no attention to the yellow cloud around me as the 11 ft Sand tiger shark ( close cousin to the great white) swims past my nose 2 ft in front of me, then right up to my wife's face.
Hope this helps