Finding a Leak on a 2010 PA14 - Advice Anyone?

My old friend has begun to take on water. There are no visible cracks or punctures in the hull. I can think of/see only two potential sources:
1) the seam in the hull at the bottom of the mast assembly: there's are a small white plastic 'plug' (actually there are 2 for some reason and one is at the base of the mast) where it's 'possible' for water to be seeping around the plug. I caulked the inside and I've never seen water coming in or out through there.
2) The space where the rudder up/down line runs into the hull. The whole is much larger than the line, so it looks like water could easily be entering the hull through there. I'm thinking there may once have been a plug of some kind that allowed the line to flow smoothly through it but created a tighter seal than having just the naked line running in/out of the hull allows. I can't find any parts diagrams or photos that show what this assembly looked like brand new.

Anyone have any advice or experience that could help?

You may want to check out this active thread for tips:
https://www.hobie.com/forums/viewtopic.php?f=11&t=62757

Check the area around where the Mirage Drive well joins the inner surface of the hull. My 2010 PA14 developed a leak there because the MD would bang against the rear part of the well with every pedal stroke. The leak was not detectable on simple inspection. But by shining a bright light on the outer hull and looking at the transilluminated inner hull in a dark garage at night, it was easy to spot the crack, which lit up brightly. This was confirmed as a leak by placing a go-pro style video camera under the deck while pedalling around on the water, and observing the area of the crack opening slightly and taking on water with each pedal stroke. I was never able to observe water leaking in when just sitting still on the lake; only when pedalling. And this led to the discovery of the mis-aligned MD seating as the underlying cause of the crack.
Good luck!

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Sounds like the rudder line sleeve lip has worn off and the sleeve slid inside the hull. This will cause a substantial water leak.

Plastic plug is just a cover over the embedded brass nut that mast tube bolts to. Cosmetic only, doesn't cover a hole to the inside of the hull. So wont leak around it. Only way you get a leak here is if it is a localised high spot and a crack forms around it, due to impact.

We have a FAQ on leak detection here:

https://www.hobie.com/forums/viewtopic.php?f=21&t=12575

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thank you all for your advice and links to more information.
Because my kayak has several cracks on the deck, I was unable to pressurize the hull.
But with a lot of sleuthing using both light and water (not at the same time!), I believe I've found the source of the leak - the drain plugs. When I stand the rig nearly straight up on end with water in the hull it begins to drain out pretty quickly. Looks like the plugs and the threads they go into are pretty gnarly so I've ordered a new set of plugs, and am hoping the 'yak threads aren't also shot. Also taking the opportunity to replace the rather beaten up skid guards, too.
Here's hoping new plugs with new seal the deal!
Thanks again, everyone!