Stringer/Transom area question

[JohnB]

I am putting an Armstrong alluminum single bracket. It is the full size one that runs the whole width. Being a Sceptre, having the "big top", and having a single 472 pound motor, I wasn't looking for alot of floatation back there. The boat was already a tad nose heavy. Also, I found the bracket for 500 bucks, which is about 2200 less than a new one, and all it needed was fresh paint. I have probably removed at least 400 pounds of "dead" weight from the boat (wet transom, wet fuel tank platform, etc). Using composits, I hope the net to be 250 pounds lighter, unfortunatly, most of the weight loss is in the stern.

[JohnB]

I am pretty much ready to start building. I ran into 2 things I am pondering,

1. The stringers are minimally attached to the hull on the inside. I suspect they may a little wet. I am going to hit it with a moisture meter this AM. I also have some concern that the glass isn't stuck to the stringers in some areas. There are areas near the floor I can push in with my thumb. Is this just because the stringers where square, and don't sit flush to the floor? or am I looking at something else. I am definitly going to beef up, and reattach the glass on the sides of the stringer back to the hull. The question is should I just cut the glass off the side of the stringer, and put new glass in on the side of the stringer where I can push it in, or just build up with glass over the existing? There are places on this string where it is attached that it is so thin, there are holes where the glass wasn't wetted out.

2. I have read so much on composites, glass, and epoxy, my head it going to explode. I am probably going to spend a little more money, and use Vinylester, vs poly or epoxy. The current option is going with 30 pound nylaboard which is 260 a sheet (OUCH), times 2 sheets, or go back to marine plywood. I have found that there are a lot of problems with separation between the glass and the composite board, especually if you don't have a vacuum system to pull it together. There are many production boats that are having these problems. My plan was to lay the composite coring down flat, and put a layer slow curing glass on top of it, and let it sit overnight. Then put a couple of layers of glass on the transom skin. Then put one layer between the transom skin, and the glass composite board. This would alow for max connection between the composite and the transom skin.

My question is this adds over 350 bucks to the project, and a plywood transom, especially one without a cutout will last 20-30 years. I don't know what the life of the hull is, but that would make the boat 40-50 years old. That is asking alot of of a hull. Really, the only major advantage is a little weight reduction, probably 100 pounds.

I know this has been tossed around quite a bit on here, but what does everyone think the weight difference would be? and has anyone had experience with Vinylester resin on a composite bonding/debonding?

[strick]

On the stringers I would grind out questionable areas with the grinder and then re glass to beef en it up. Myself I don't think there is anything wrong with using plywood as long as you do it right. I've used both epoxy and vinyl ester over foam coring material without any problems. Don't worry about debonding your plan sounds OK but you will need to thru bolt the transom core with something on either side of the transom say 2x4's to suck the new transom coring to the outer skin. If you use plenty of resin you should have no debonding issues. One thing to keep in mind is that some of your transom coring materials are so dense that they are nearly as heavy as plywood so the weight difference would be negligible. I would do all your repairs in epoxy and for making parts use your vinylesters and polyesters. I used vinylester on the majority of my 20 restore because it was a little cheaper then epoxy and I wanted to see what working with it was like. The fumes are a real PIA but otherwise I'm happy with with it and it appears to be plenty strong.

strick

[JohnB]

Thanks Strick,
I am leaning back toward marine plywood pretreated with epoxy, and puting it back together with vinylester resin.
If done poorly, like mine was, with unsealed holes for years, it almost made it 20 years. I don't know what the life of a hull is, but if it makes it to 40 with plywood, I won't complain. At 270 a 4x8 sheet, times 3 sheets, it really is piling up.

[strick]

I would not vinyl ester over epoxy. You can epoxy over just about anything.

strick

[JohnB]

I am using epoxy for everything except the cap, panels, and live well.

Here are some more pictures
I used 2 layers of biaxel tape to retie the stringers back down. It came out very well. I put a block of wood against it, and smacked it a couple of times with a 3 pound sledge, and it is all VERY solid/tight. That tape with epoxy is amazing.



Here is one of the things that drives me nuts with these boats. The sole to stringer connection, or in this case, disconnection. There is a 1/2-3/4" gap, and right above the stringer, and in addition, the sole is not level or straight. Like I said before, this thing must of been made on New Years Day, after a big party.



So far,
- I have repaired the stringers, and retied them to the hull.
- I have leveled, repaired and glassed in the sole to stringer connections on both side of the fuel tank.
- I have replaced the forward and rear bulkheads in front and behind the gas tank.
- I have put in the new gas tank platform, and have the transom cores cut and ready to put in.
- I have the donor panel made for the outer transom cutout fill in.

In case you haven't seen what a mold table looks like, her is a picture of what you can do with an old sliding door


Here is the before and after of the sole "floating" on top of the stringers, where it is now solidly attached.
Before - the sole just had glass putty stuck under between it and the tops of the stringers, it had come loose in several places, and wasn't level.

After - it now feels like you are standing on concrete.

Here is the fuel tank deck and bulkheads put in. Notice the 2 notches to let water in/out. I am going to put the gas tank on 1/4" neopreme strips, and attach it with mounting brackets to the stringer, no more foam to hold water.


and today, I just finished preping the bracket for powder coating, and tabing in the transom outer skin panel.

[JohnB]

Well, the gas tank should be ready to be installed next week, picking it up Tues. I am getting the 1/8" tank, vs the 3/16th. The old one was 1/8", and was over 20 years old, and no leaks. The issue was more of weight than cost. The mounting platform, and installation will be much better than the original, so I would hope to get 20 or more years out of it. I am now knee deep in fairing freenzy to get it all leveled and cleaned up.

I built a mold to make the cap that would fit in front of the transom. The livewell will be mounted inside the cap. The cap came out real good, and fit within 1/4" everywhere. I took the old SeaCraft livewell hatch that was in the floor, and reused it. I wanted to keep the classic appearnce, and also, I'm cheap. Here are some pictures of the cap





I finished the mold for the livewell this afternoon, and have to do a little clean up on the corners, but it should make a nice livewell that will fit inside the cap. I left the boxes and lids in the back, so the geometry is 12" to 17" wide, 44" across, and 21" deep. It calculates at about 38 gal, but will probably action be about 34 when full. If anyone need a livewell that will fit inside a transom cap, let me know. I will keep the mold around for a little while. I plan on putting an adjustable height standpipe/drain in it, so I can adjust the water level height in it.

[htillman]

Nice work. What type size outboard powers your boat. I used Coosa on the transom mainly because I could get it in correct thickness. It was more expensive but is also providing great ways to build braces and supports. Funny, the port side stringers in my 23 are wetter than the staroard. The bottoms are wet indicating wet foam but structureally in good shape. I will post some pictures but I have found two cracks in the bow area in the lower cap right at the forward storage area. Looks like she was run pretty hard on a rough day. The moisture meter you recommended really detects wet areas and seems to be real accurate - sometimes scary.

[JohnB]

I am currently running a tweaked 250 EFI Merc offshore, probalby about 310 hp. Lots of power, but 1.7-1.9 mpg is putting me in the poor house at 3 bucks a gallon. Long range plan is to put a Suzuki 4 stroke or Merc optimax 300 on her. Pick up a little speed and a lot of milage.

As for the coring, I drove my self nuts looking at all the options. The original core lasted through 20 years of abuse and poor installation from the factory, if this one goes 25, that will be fine with me. I went with Okumi marine plywood, and all the layup was done with epoxy, 4 layers of it. We have seen alot of transom failures in foam core boats (I won't name names). I think if they used epoxy instead of glass, they wouldn't have as many problems, just my opinion. I used dyvincell to recore my hatches, and the stuff has worked great.

For whatever reason, all the seacrafts I have seen that have one stringer bad, it's always on the port side, wierd. For you stringers, I would drill some 1/4" holes ever 12", right at the bottom of the stringer, and let it drain for a long time, maybe put some heat on it, I used hair dryers. Then plug the holes, knock some 1/2" holes in the top, and pour slightly thickend slow cure epoxy in to "reconnect" the cores to their outer skins, and then run some 45 degree bixal tape down the sides of the stringer to reinforce the stringer to hull connect, I used to layers of 9 oz/6" wide the whole length of the boat.

The cracks in that area are usually because the lower cap is now lose from the top of the stringers and is moving around. Most of them do that, especially when they have seen as much water as mine has.

[htillman]

Good idea on drilling the holes in the stringers. I have drilledone on each end and found water weeping out. I will now drill as you recommended and use the heaters. The hull and top cap are stored indoors and have not seen water now for three months. Plans are to keep both completely dry until I reinstall the top cap. This will give me time to continue drying the stringers. What surprised me is the floor is solid. The moisture meters reads damp in a few areas but is for the most part solid. The last 23 I had the boat cosmetically looked much better but I had two soft spots in the deck that I injected expoxy in and stiffened. I need to recore the hatches as they indicate very wet and are a tad heavy. Need to look into some composite coring for this project but I may wait until next year on the hatches.
I am looking at a 5 year old 250 Johnson for power. My friend has it on the back of a 76 23 Sceptre and wants to repower with a 300 Suz 4 stroke. Claims that is the engine for this boat. He purchased Potter built tackle cabinets after Potter left Seacraft. Very nice boxes. The tackle cabinets are old but in good condition. He has owned the boat since less was less than one year old and is a Seacraft fanatic. Actually has a very old 20 Seafari that still runs in original condition.