Stringer Construction Question
 

Hi guys, been following the site for a long time, been a SeaCraft addict much longer, just joined recently. Owned several over the years and built/re-built most of those, so I'm not new to the addicition many of us have.

I just finished gutting my most recent project. It was 1970 20' I/O, it's now an empty hull. Once apart I realized the stringers are completely hollow.
I can tell the rear portion of the stringers (where the original motor mounts were) had wood that has rotted away.

My question is, would the original stringer system been hollow, or is it more likely they were completely wood and have totally disenigrated?

Thanks in advance

If there were four stringers, they were wood cored. If there were two box stringers, they were originally foam filled. Since yours is a '70, I would assume the four wood cored stringers unless it has undergone a previous restoration. I think Potter switched to the box stringers in '72 or '73.
Dave

Dang, not the answer I wanted to hear. Boat has four stringers, didn't want to tackle stringers, but oh well!

Funny, my 1977 20 was also an I/O, has four stringers, but those were foam filled except where the motor mounts were located.

Seems the more I learn about these boats, the less I really know!

Don't tear out your stringers yet! I can't say for sure that your stringers were wood cored or if the wood cores were structural. There are others here that can probably offer more informed opinions. Get a consensus before you do anything.

Dave

This is a wondeful racehorse.

The old 4 set up looks like some other reason to think about great thoughts.

Tabs between the steps. Think like Carl.

I want that race boat.

Nuts,
GFS

If you want to find a real clear description of the 20' hull construction, click on the Classic SeaCraft Home link at bottom of page, go to Literature tab, and read the 1969 Boating Magazine article on the 20 Seafari. (If you can't read it, send me a PM with an e-mail address and I can send you a clearer .pdf file of it from original article) That article contains a very detailed description of the hull lay-up/laminate schedule. From that article, I concluded that the stringers were laid up separately and installed about half way through the layup, and I believe they were hollow. The stringers on my boat appear to be hollow, although it makes sense that they would have used wood near the aft end for the engine mounts on the I/O models. If there was any foam in them, I suspect it may have been installed when the rest of the floatation foam was added, just before the inner liner was installed. The 4-stringer set-up was Moesly's original design and continued through 1972. It appears that Potter changed to the 2 box stringers in '73.

I can only add a little to all this good info. There was always wood where the
 

Engine was Lag bolted down to the stringers back then. So you will find rotted wood in that area on IOs On OBs the transom is usually rotted. The rest of your stringers should be good to go. Bushwacker sure does have his seacraft history down. I have worked and owned moesely and potter sea crafts and have found them way ahead of the curve back then compared to all other boat construction.

"Seems the more I learn about these boats, the less I really know!"

Dreamer,

You have happened on the most important lesson I ever learned in this life, which is;

The more I learn, the more I learn I'll NEVER know!"

If the stringer is hollow that really does not matter. All the strength comes from the box construction. The wood and later foam is only there for making the mold or box. If the glass on the stringer is in good shape (bonded to the hull and not separating. Just add more glass around the stringer box and you should be good to go.

If you go to page 2 of my build section about half way down you will see what I am talking about.

Have fun, that is half the battle.

Thanks for all the replies guys! I like the thought of not redoing stringers.

Another question/thought- I'm assuming the flotation foam was used as part of the "support" for the stringer system. Since i have to replace this (as some of it a saturated), and there was nothing in the middle of the bilge, would you guys foam this in (to help with support) and leave the tank in the console, or put a tank in that space?

Hi
I have a 1969 that i have started to demo and i can tell you that they are hollow with a strip of 3/4 plywood about half way up nailed in. looks like it was there just to hold the shape.

This is what I found on my 1969.

On the first page: http://www.classicseacraft.com/commu...ad.php?t=17024


Not sure I'm understanding exactly what you are asking. Foam "OUTSIDE" of the stringers and in between them was placed there for water displacement.... thus extra flotation should the boat swamp...... not support. Foam "INSIDE" stringers will help a little with structural integrity but is mostly there for the same reason ...water displacement/flotation. As far as what to do with the fuel tank.....I would put the fuel tank " in between" the stringers.

strick

Strick,
I gotta read the whole thread about your re-build- looks great. Right now mine is is the stage you started minus a transom (lots of supports holding the shape right now)
Do you have any thoughts on fule tanks placement should I decide to put it below deck? Thinking a fifty gallon tank, would you push it to the step up , or center it between the Transon and the step up?

thanks again to everyone for your input!

I would push it so the front of the tank is almost touching the step up. I could have pushed mine a foot and a half or so more forward and plan on doing so some day if I ever have to take off the fuel hatch.

strick