what is the function of the keel stringer?

mada · #1 09-19-2003, 08:54 PM

On the older (70's) 20 cc boats, what is the function of the keel stringer (the laminated piece that runs the length of the boat. It's the only active core stringer on the boat and is totally rotten in most of the hulls of this vintage.

A few experienced boat builders have told me that the keel stringer core does not really lend much at all structurally, it's the glass doing all the work.

This is 2x4 with a rounded top that runs the length of the center of the boat.

If the 4 main inactive (hollow) stringers are in good condition, is a wet core in the keel stringer a problem?

Any feedback and knowledge would be great.

Finster · #2 09-19-2003, 09:13 PM

Carefull who you listen too. If people are telling you it worthless or do not know the purpose of it, you may want to find others who do.
Think in geometric terms for that stringer, hollow or not.

And no my '72 23 ('71 production) is not rotten as you may think.

FELLOW-SHIP · #3 09-23-2003, 09:31 AM

This is a great question I whish I really knew the answer to it. I have the 23 and with the longitudinal steps plus the foam filed stringers I also was wondering if that center wood stringer war really needed. But I would rather have a Ocean Boat that is over built then under built any day. I don’t get any flex in the hull when I am going through 2’ to 4’ and everyone that goes on my boat says it rides like a Cadillac. If that stringer helps provide the ride that makes the old SeaCrafts have the reputation it does than “I Like That Wood Center Stringer”.
FellowShip [img]images/icons/cool.gif[/img]

GetReel · #4 09-24-2003, 05:24 PM

Yeah, I would also like to know just what specific purpose it serves, it must lend rigidity and would it be seriously compromised by moisture? Can someone answer the question?

Capt Chuck · #5 09-24-2003, 08:47 PM

My 78 23' has the same rounded stringer but I thought it was half a PVC pipe glassed over??? I have never heard the wood deal before and I've owned two seacrafts since the 70's. Anyway I do know that there should be a piece of nylon rope sticking out the side of the box foam filled stringers(aft inside) This rope acts a a "wick System" (like a candle) and any moisture that builds up in the foam will follow the wick out and drain in the bilge. I have seen the same system in the "Haupner" flats boat built by Ocean Master here in Jupiter fl. Wonder why they have the wick system? Bill Potter was working with them in design!

Capt Chuck (shellback)

Remember if she asks"how much did that cost?" LIE!

[ October 31, 2003, 08:22 PM: Message edited by: capt chuck steele ]

abl1111 · #6 09-24-2003, 09:27 PM

Capt Chuch,

Nylon huh ? Where exactly was this pc of nylon. I'm in the process of re-doing my boat and have not seen this. It makes sense though, the moisture will head to the lowest point.

I will re-install this if you can tell me exactly where she goes.

Oh, and I have wood stringer too. It makes sense that it adds some rigidity between two opposing sides of the hull...

Capt Chuck · #7 09-24-2003, 09:43 PM

abl1111

I don't know about reinstalling this wick or not. I think it might run the entire length inside the box stringer like a candle? I almost cut mine off the first time I discovered it as I thought it was the plug they used after pumping in the foam or something during construction that they left in there. For example: If I go to the round inspection plate at the transom on the port side and take my left hand and reach in pushing my hand forward toward the bow between the inner liner and the stringer I can grab the wick. It's about 1" diameter and approx 5" long. I don't remember what the hell I was doing in that position to begin with when I discovered it but "viola"

Capt Chuck(shellback)

[ October 31, 2003, 08:24 PM: Message edited by: capt chuck steele ]

mada · #8 10-05-2003, 12:13 PM

It would be great to hear potters response.

I look forward to hearing his reply to this.

If you could...

ask him how it could lend to the boats stiffness if the 4 main stringers are so stocky and overbuilt.

mada · #9 10-05-2003, 05:00 PM

I should have been more clear...

my concern was with dampness, not rot...however, they are all too often related.

Thanks again for your help with this. Any relevant info on the stringers and their relations to each other would be helpful.

Trayder · #10 10-05-2003, 06:41 PM

Mine was rotten. I tore it out and replaced it with 1/2 round 4" PVC/ I then covered the PVC with 2-3 layers of roven woven.

I use the inside of the 1/2 round as the drain to the bilge from the fwd compartment.

My Contender uses the same theory, I just copied it.

Give me a year or two to tell you if it works but so far so good.

I have been able to lift the hull up with a floor jack, placing the jack directy under the bottom center of the boat, so replacing the wood with PVC/ Glass has proven plenty strong.