I have the opportunity to pick up a 24' SeaBird, fully rigged for offshore with a new 225 Yamaha
for very cheap
(for those that dont know...SeaBird is a very well built, older boat...with the same hull design as a Contender)
The boat is, however...old
It has a little bit of wood rot...but, otherwise looks just like a $50,000 Contender.

I know a guy who restored one once...it involved separating the deck and hull, and replacing the wood stringers and such with a foam alternative.
It is supposed to be just as strong, yet much lighter.

Anybody ever done anything like this before?

If you planning to seperate the deck from the hull, you have to build a cradle for the hull,
support the transom, and all the way up the keel, if you don't the hull will twist when seperated.
your better off using Marine grade plywood for the stringers, they maybe not lighter but if
you use the foam type the hull might distort when re-joined, make sure that you use brass
screws for everything, steel ones is a no-no for marine use.

Quoted: I have the opportunity to pick up a 24' SeaBird, fully rigged for offshore with a new 225 Yamaha for very cheap (for those that dont know...SeaBird is a very well built, older boat...with the same hull design as a Contender) The boat is, however...old It has a little bit of wood rot...but, otherwise looks just like a $50,000 Contender. I know a guy who restored one once...it involved separating the deck and hull, and replacing the wood stringers and such with a foam alternative. It is supposed to be just as strong, yet much lighter. Anybody ever done anything like this before?

Nice.  Sounds like it'd be a bit of work, but if I were you and in a position to do it, I'd jump on it in a heartbeat.

Besides which, it'd be useful if the fertilizer ever hits the ventilator -- load the boat up (if it isn't already) and GO.

Quoted: If you planning to seperate the deck from the hull, you have to build a cradle for the hull, support the transom, and all the way up the keel, if you don't the hull will twist when seperated. your better off using Marine grade plywood for the stringers, they maybe not lighter but if you use the foam type the hull might distort when re-joined, make sure that you use brass screws for everything, steel ones is a no-no for marine use.

How big of a "can-o-worms" might I be getting into?

This is a 24' center console, open fisherman.
The main reason I am thinking about replacing the wood is because there are a couple of slightly spongy spots in the deck...and some staining in the bilge that I believe is from rotted wood.

If you live close to any marina, go check them out, when you see a boat thats almost completly
coverd with 2x4's and 4x4's posts, thats what they are doing, you just can't replace just the soft spots, like on the transom, you have to replace the whole transom. I worked in a Marina for two
years in Kehma Tx, on the gulf coast. there is no easy fix for rot on a boat. you got alot work ahead of you, sorry....

Quoted: If you live close to any marina, go check them out, when you see a boat thats almost completly coverd with 2x4's and 4x4's posts, thats what they are doing, you just can't replace just the soft spots, like on the transom, you have to replace the whole transom. I worked in a Marina for two years in Kehma Tx, on the gulf coast. there is no easy fix for rot on a boat. you got alot work ahead of you, sorry....

thanks for the info

There's a book called Runabout Renovation you might look at, as well as Fiberglass Boat Repair and Maintenance by Gougeon Brothers.  Some alternative methods, like drilling a bunch of holes in the stringer and injecting with epoxy, are looked at for fixing this sort of stuff.

For replacement of the stringer, you want to totally encase the stringer in fiberglass, and try to maintain the same stiffness as was originally present in the boat.  Otherwise, you can form "hard spots" on the hull which can lead to cracking.  This means trying to use the same type and number of fiberglass layers on the stringer.

Laying in the glass is fun, but getting it out is nasty, dusty, itchy work.  WEAR A FILTER MASK - and not one of those cheesy one dollar ones either - I mean a real mask with filter cartridges.  Home Depot has them for about $35.

epoxyworks.com
westsystem.com - go to the "Product Guide" tab and look at the instructional publications

This could turn into a real nightmare for you once the deck is stripped and you see the inside.

How cheap is very cheap?