15 year empty wooden hot tub problems

[MrCrowley]

Hello Folks,
I am trying to get a hot tub left to me in a home by my father RIP to hold water. I added like 3 inches of water to tub sll leaked out bottom somewhere (after fixing plumbing problems) the tub was left empty for 15 to 20 years because of plumbing problems wood inside tub is dry as a bone and the rings are starting to become loose (3 ring's around tub) . Before I go any further should I be prepping wood with some kind of treatment I am guesing to help it expand to hold water. Any help greatly appreciated Thanks
Mr C

 

[Thimble]

A trick old timers used with barrels and buckets was to stuff them full of straw and keep the straw wet. It would swell the wood to the point the vessel could hold water long enough to be filled and complete the process.

 

[OldPoolMan]

There used to be a wood hot tub sealer product called Tub of Gold. Worked pretty good Maybe look it up online