Firstly, I wouldn't be so sure that's where the water is coming in to the boat. Centerboard wells, rudder gudgeons, ports and drain ports are the usual culprits.

The time-honored way to find out for sure is the soap test, similar to the way mechanics find holes in car tires. Take a vacuum cleaner. Run the hose to its exhaust. LOOSELY, and that is a MUST, run the vac exhaust to the drain on your hull. Rather aim the vac hose at the drain and duct tape it to the hull, just enough air to get in and create gentle pressure on the hull.

Fill a spray bottle with soapy water and spray the hull. Look at bow tangs, shroud fittings, centerboard wells, ports, rudder gudgeons. If they bubble, well, there's your problem.

To check the drain ports, screw in the pluts, take the vac hose and again LOOSELY hang it in a port, sort of sealing it with duct tape again. Just get some pressure on the hull. Spray the drain plug port and look for bubbles.

If the bungee tubes are indeed where the leaks are, the easiest thing is to just plug 'em with exterior grade silicone. Otherwise, seal whatever leaks with silicone or fibreglass your board trunks.

good luck with it
sea ya
tami