74 Proline 24

[JTB Boatworks]

What's up everyone.  My name's John.  I am rebuilding a 74 Proline 24 flatback.  I plan on documenting the build here in hopes of getting lots of valuable advice from everyone along the way.  The plan is a simple bay boat, 200ish Yamaha on a porta bracket, hard t-top with mid or full tower, etc.  I'm currently gutting the hull to be able to start on transom and stringers.  I look forward to sharing this with you all. 

[JTB Boatworks]

So first question is on the transom.  I will be going with a full transom and getting rid of the notch.  Is it better to maintain the factory integrity of the original skin of the transom or better just to cut the whole factory transom of and start fresh with melamine and new glass?  Going to use coosa for the core material.  For the core, is laminating thinner pieces stronger or should I be trying to buy the thickest sheet I can to avoid laminating?

[Tampa Bay Mike]

Nice looking boat. Should be a fun build. 

For the transom, you'll probably hear about 50/50 each way so it may become a decision of what's the most cost effective. The last time I was at marine surplus down in Sarasota they had a few sheets of inch and a half left for about $300. May be worth a call at least.

[RickK]

If the outer skin is not too holey, you can leave it. If it is wavy you might want to cut it out. You'll still use a a sheet of melamine either way to give you a flat place to add the notch fill in and to get 3 layers of 1708 on the inside of the skin to start your rebuild nice and beefy.
As for the core - I agree with Mike.

[JTB Boatworks]

Thanks guys.  I will check with marine surplus Monday.

[Capt.Joe]

My transom skin was cracked and had several holes. I was going to try and salvage it, but took the advice from the guys above and cut the center out completely. For me this was the best method.

Now the majority of my transom is new and the entire back is even. If I went through all of that trouble of new glass while trying to save old skin, I would’ve been kicking myself. I hope this helps and welcome to the forum!

[JTB Boatworks]

Been working a little every day on the demo.  This boat has definitely been through a partial rebuild by someone just trying to get by.  They reinforced the deck with pressure treated 2x4 between the stringers.  Between all the extra wood and the water logged deck the boat has easily shed a couple thousand pounds the last few days.  She should be about ready to start selective demolition and replacement of the transom and stringers soon.  I noticed after the replies related to my transom questions that my transom also has a lot of spider cracking and holes.from different hardware over the years.  I'm really leaning towards replacing the whole thing with 2 sheets of inch and a half coosa laminated together.  I'm thinking of using doubled up 3/4 coosa for the stringers.  Going to stick with the 4 stringer setup that is original to the boat  just needed up.  Might have to get creative to incorporate the fuel tank into the floor as it was in the front deck originally and the stringers and pretty narrow.  What is the standard size PVC to use for the rear drain hole in the boat?  It appears this one was moved down over the years but not low enough because the boat still holds water even with the tongue jack all the way up and on wood blocks.  All input is appreciated.

[RickK]

Garboard plugs are usually 1" OD.
If you are unsure of the condition of the transom outside, take a flap sanding disc on a angle grinder to it to see that is below the gelcoat/paint. You can find the flap sanding wheels at harbor freight and any of the home improvement stores and can get them in from about 24 grit on up. I would probably use an 80 grit to grind down the aft of the transom.  The 24 and 36 grit discs are good for grinding the hull inside. Flap sanding wheels make short work out of  anything you touch with them.

[wingtime]

Two sheets of 1.5" Coosa is way overkill for the transom.

[Tampa Bay Mike]

Two sheets of 1.5" Coosa is way overkill for the transom.

Agreed. Two sheets of 3/4" seems a bit much for the stringers as well.

[JTB Boatworks]

I will look into some thinner material.

[RickK]

1 layer of 1.5" is plenty.

[mshugg]

Agree with Rick, a single layer of 1 1/2” Coosa is perfect. If you’re replacing the stringers it would be solid too.

[JTB Boatworks]

Thanks guys

[JTB Boatworks]

Does anyone have any pics or recommendations on a cradle for rebuilding a boat that is on casters?  My thoughts are this would make it easy to roll out of the barn for the big grinding jobs during the rebuild.  I've seen a guy use wheel dollies from a car that seemed to work pretty well.  Also, I know I need to support the 2 rear corners as well as the bow, but are there exact spots to support the boat for transom and stringer replacement?