Need help with stringers

[jcvfl]

This is my first boat and I attached pictures. Its a 19ft Marathon Bowrider, 4.3L OMC I/O. It needs a new floor. The previous owner put in new floor, but didn't seal any of the holes he drilled into the stringers, so the floor rotted out again, and the stringers rotted out. Pretty much all the stringers need replacing, some have turned to dust. The old fibergalss that covered the stringers is still completely in tact pretty much, so my plan was as follows:

Cut the tops off the fiberglass (and the stringers), clean out all the wood from inside, then replace with new wood epoxied to the hull and fiberglassing over the entire thing several times also with epoxy.

My first question, obviously, is will this work and is this the correct way to replace them?

My second question, deals with the design of the boat, I guess. The middle stringer up at the bow of the boat has a notch cut out of it with a piece of fiberglass going across the top of the notch and against the stringers on either side. Its the first picture I attached. It looks like some kind of drainage system or maybe its something else. Could someone explain this to me so I can better understand what I'll be replacing?

Any other info will be greatly appreciated. Thanks.

[jimslade]

This is a great example of a boatbuilder who has little knowledge of structural forces in the marine enviroment. My suggestion, which would not be popular, is to run four full length stringers. Wood will work but there are better options.I could post some pics of a 17 ft bowrider I'm working on. I used nidacore for the stringers and transom and floors. No rot ever again.

[jcvfl]

Please post the pics and any other info...!

Do you mean I should run 4 full length stringers from back to front and the one in the middle at the bow? There were 2 ribs going across where the empty notches are (you can see where they were in this next picture).

I'm still confused with the section in the middle, where you walk through to the bow. Is that just bad boat design, and should I use a full size stringer running back to where the gas tank starts? Or should it have the notch cut out with the 2 ribs?

Also, any idea why that piece of fiberglass is going across the top?

I've been trying to find out more about alternative materials. I wanted to use some type of foam core or other non-wood material for the floors, but I wasn't sure if about the stringers - would it affect the way the boat ran through the water, etc. I'd love to know more.

Also, any chance of the hull getting warped or misaligned somehow? I figured if I do one stringer at a time it should minimize the chances...

Thanks again.

[jimslade]

Check out "cores in hull bottom" thread, there is a pic there on the second page. Set the boat on three points. Back two outside corners and the front bow where it just starts to curve up. Do one side at a time. You will find that the back 5 ft. of the boat will have a hook in it.(not straight). I would straighten this once your done. It makes the boat run faster and true. The ribs you have are side supports. You should have them every 5 ft across the boat for lateral support. Use the placement that you have for the stringers and extend and taper them up into the bow section with the laterals every 5 ft. Make sure that the centre area of the stringer does not touch the bottomof the boat.

[jcvfl]

Could you elaborate a bit more - you sort of lost me....

You saying set it on 3 points to prevent it from mis-shaping? I don't understand what you meant about the back 5ft of the boat having a hook.

I had 2 laterals, shown with the red rectangles in the above picture. Behind the 2nd lateral, is where the gas tank starts, and it extends to the back, therefore not giving me room for any more laterals.

Do you mean that the 4 long stringers that are there now should extend up to the furthest front end of the bow?

Also, what do you think about that middle stringer?

[jimslade]

If you set it on the back outer points,(transom) there is little pressure on the bottom to flex in while working on it. Check the last 5 ft. of the bottom with a straight edge. Most boats are not straight over the years. Also some manufacturers put a hook there to limit the top speed for insurance reasons. The laterals can run just from the outside edge of the outer stringer to just short of the sides. Sorry for being short and not elaborating, I have responded to these same questions many many times. I could go into specific details if you want to call my shop sometime. from 8-7 mon to sat . I live in toronto canada even though I wish I lived near my sister in Lakeland Fl. #905-640-1123

[jcvfl]

I can search through the older posts for that info, and I appreciate the input... I'd like to know if you, or anyone else, could give me some advice as to that center stringer with notch and the lateral...

Thanks

[jimslade]

The centre stringer is a bow stiffner. It is more for pulling on the bow eye than for stiffning the bow. I would leave it in and tie it into the stringers just down from the tank support wall.

[jcvfl]

I appreciate the help and that was exactly what I was planning on doing - just that it has like this notch cut out of it with a skin of fiberglass which extends all the way up to the front and around either side of the stringer. It looks like the notch was cut out to make room for the frontmost lateral.

I'm not sure if I should duplicate this or should I make the center stringer without the notch?

Also, your first reply you suggested I run 4 full length stringers - did you mean the four that are there now (2 on either side of the center) should be longer and extend up the end of the center stringer?

Thanks again..!

[jimslade]

Yes extend the stringers up to the bow section.

[jcvfl]

Thanks, Jim... You know, I've been searching this forum for more info, however, it seems that posts are only kept for a certain amount of time. I've found posts where people say "Check this post for the information on stringer repair." and the link comes back broken. It would be nice if this forum had a "sticky" feature so that newbies like myself could fin certain info quicker, and others wouldn't have to repeat themselves...

This is my first project, and I'd like to get more information. If anyone can provide a link to more information, I'd appreciate it. I'd like to find out the proper way to connect the stringers to the lateral ribs and transom, for example.

[jcvfl]

I just came across these foam stringers:

www.preforms.com

Anyone ever use these or know if they're any good?

[PAR]

Jcvfl, I'm just north of Orlando (Eustis). The repairs you're attempting are very common and well covered in the archives on this forum. Sometimes you have to run several searches to get what you need. Your "user CP" may also need to be updated to permit you to see older threads. If you'd like to call or email me, click on my name and drop a line.

[SamSam]

Here's another place where what you're wondering about is discussed a lot. Click on 'forums', join and ask away. Lots of photos, also. Sam
http://www.iboats.com/