60's Sportsman runabout

[bobberboy]

Today I got inside and scrubbed most of the oily gunk out of the inside. I hadn't bothered to take the foam out from under the splash-well so I finally got around to that too. I was probably in denial about that last bit because, as I should have known, I finally got to see the bottom inside of the transom and yes, I have to take it out and replace it. Dang it anyway. There's a built-in design flaw that could only have ended in the transom having rotted away (red ellipse). You can see in the photo below that the stringers running the length of the inside attach to the transom with screws. There are three on either side of the center following the curve of the bottom. Water drained to the back of the boat between the stringers but there was no accommodation made to drain the water down to the center and out the drain hole so water was trapped on the upper side of the stringer (green arrow). I'm going to have to drill holes (blue arrow).



To do a proper job of it I should take out the splash well rather than try to slip the wood past it but that's a mean mess of rivets to grind off and remove, plus three drain holes. The plywood is a single thickness or I'd see if I could cut off the bottom half of the inside sheet if it were two 3/4" pieces glued together. You can see how many rivets I'll need to take out in the two photo's that follow. The last photo shows the cast corner pieces and the bent cap on the top edge held on with headless nails. This a drag and I'm not looking forward to having to do it.







Can anyone explain the rivets to me? I'm not sure how to replace them. I'm familiar with pop rivets but these are factory jobs and I don't know if it's possible to replace with the same kind. What I really wish is that I could dry the wood and impregnate it with resin or something that would prevent any further rotting and also consolidate the wood that's there. I'm going to look into any alternative I can to avoid doing this. Any suggestions would be appreciated.

 

[ccm]

If it's rotten it's rotten. There's no other way around it but to rip it out. There are two ways of doing hard ware for the transom.

1. Factory style with aircraft grade solid rivets with you & a bribed buddy hand bucking or investing in an air hammer with a proper attachment along with a bucking bar. Long & tedious process to do it properly.

2. Replace as many of the main rivets in the transom as possible with SS bolts washers & lock nuts ( all of the ones below the water line & through the transom wood ). The corner brackets/L brackets on top can be put back on with pop blind rivets/closed end rivets. Seal all of the SS bolts going through the transom with a dab of 3M5200. This process does not take as long as the previous one mentioned but is still time consuming and a pain in the rear to do.

No body wants to replace a transom & I dread the day I have to rip out the original one in my 1961 Sea King built by Arkansas Traveler. It has a total of 76 that will have to be removed in order to get it out. I have gone to great lengths to sand & reseal it so that maybe just maybe I wont have to do it. The best of luck to you, ccm.

 

[ccm]

Just counting what I can see then multiplying by two. Only counting the 4 in the middle of the transom once & I'm not counting the ones in the L/corner brackets. 26 x 2 = 52 + 4 = 56. So I'm guessing around 56 SS bolts, washers, locknuts, & a tube of 3M5200. I believe you can reattach the L/corner brackets with closed end pop rivets.

 

[bobberboy]

Thanks for the replies - I guess I knew there wasn't much of a choice, but people here are creative and figure stuff out so I was hopeful. If I could leave the splash-well in tact I could avoid about half the rivet replacement. The splash-well isn't actually attached to the transom, it's riveted on each side and the front is attached to the extrusion running cross-wise but the metal is only bent up against the transom. Maybe I should start there and see whether or not I have to take it completely apart. I recently saw a post about the drain holes in the splash-well but the drain at the bottom is a concern to me. I'll have to look again to see how it was installed and what's involved in taking it out.

 

[bobberboy]

I've been doing a little research on the possibility of restoring wood with mild rot or dry rot. There are lots of examples of ships that have been restored either as wrecks from under water or from burial mounds. One famous example is the Oseberg ship in Norway. It was recovered from a burial mound dating to 834 and was excavated in 1904-05. The wood had to be treated to stabilize and consolidate it after having been buried for 1,100 years. It is now on exhibit in Norway.

Here is the ship as it was being excavated from the burial mound



Here is the ship as it sits in the museum



If you are an extremely wealthy chemist with a lot of time on your hands, the methods used to conserve the Oseberg could be applied to your rotting transom. I am none of those so I started looking to see if there weren't other methods that a poor non-chemist might be able to use. I came up with the following that may have some potential, depending on how much damage has been done by rot/dry rot. I don't have any personal experience with the products but the first got some pretty good reviews.

https://www.jamestowndistributors.com/userportal/show_product.do?pid=1269

The second one takes quite a bit of time to cure and may not be practical if you ever want to get your boat back on the water.

https://www.preservation-solutions.com/blog/how-to-treat-waterlogged-wood/

I don't know if anyone here has had any experience with these kinds of materials. If so it would be good to hear from you. As the rot on my transom doesn't seem to be too extensive, I'm going to further investigate the resin product from Jamestown Distributors before I make any decision about replacing my transom.

 

[bobberboy]

I don't feel like dealing with the transom right now so as a way of stalling I started to work on the interior today. I'm trying to make some decisions about a couple of things.

First is the floor. I can't decide whether to follow the contour of the bottom or make a flat floor. Following the contour would in some ways be easier and give a deeper interior. As this isn't a fishing boat I don't suppose standing on a flat floor is necessary. Making a flat floor would make the rest of the interior work easier because I'd be starting from a constant, level surface.

Once I decide there is the question of the material and finish. I had originally thought to make a slatted mahogany floor. I could do that either with the flat or contoured floor. The real question about it is whether doing so is going over the top. This isn't a Chris Craft and never will be. It's a boat made by an irrigation company in Nebraska trying to stay afloat during a slow sales period. I don't want to give the boat delusions of grandeur and I especially don't want to end up polishing a turd. At this point I'm inclined to make a flat floor and carpet it.

I put some pieces of wood across the ribs to get a sense of the floor line and where I will need to add support to make it flat. I think I ended up with about 20" from floor to gunwale. The interior of the boat is such that I can add the support without any more holes below the waterline. There are enough structural members I can attach to and the framing seems pretty straight forward.

Next I began looking at the placement of the seats and dividing the inside. I think I am going to divide the interior like I originally planned with "bulkheads" to create three separate cockpits. I have seen examples of small aluminum runabouts that were configured this way so it seems like it would be an ok thing to do. I had to make a guess to begin with where the front seats would go because I haven't decided what I'm going to do yet (bench seats or individual seats). I was mostly trying to see what kind of building issues would come up and work out some of the design details. The following pics give some sense of what's likely to happen.

You can see in the first pic the 1x1's that show what the flat floor will look like. The two plywood cross members will be the top of the "bulkheads". I'm going to make the vertical dividers from mahogany plywood with lots of marine varnish and I may epoxy the edges to be double sure no water gets in.



I'm going to make the tops arched to match the curvature of the hood. The radius of each will flatten out as they go towards the back so the hood curve is greatest flattening out at the transom.





I'm going to trim the inside with mahogany following the shape of the gunnels and curving into each of the cockpits. There was a funny detail in the front where the hood meets the gunnels with a little notch that abruptly ends the hood. I decided to start there and draw a straight line to the back where the gunnels transition into the cast corner braces. This creates a straight inner line and the outer follows the curve of the boat.

String line from notch at hood to corner brace at back.



Red line shows the notch location under all the tape.



All the cardboard and tape will eventually be mahogany plywood/hardwood.



The rounded detail on the inside corners of the cockpits.



I'm going to make the middle section larger than you see here. The way back will have a flat cover and the gas tanks and batery will be back there.



I guess the transom and floor will be next and I'll just work out the details from there.

 

[bobberboy]

I didn't want to do it but I started to take things apart to get the transom out. So far it was easy enough. The only tricky thing is to drill out the rivets in the center so as not to enlarge the hole. I first used a 3/32" bit to get an accurate pilot hole and then used a 7/32" to drill out the rivet. The rivets were 3/16" so the 7/32" should be the right size for the replacements.



There were 10 rivets on each side that came out easily.



The only hard thing was the drain holes. I tried a long blade on the Sawsall but couldn't make it work. I resorted to a cold chisel and made a real dog's breakfast out of them. I suppose it won't matter in the end because they need to be replaced anyway.



So now I can see what I've got to work with. The transom was actually pretty sound except for the bottom edge. I had hoped not to have to go through this step but the consensus was to go ahead and do it the right way.

 

[ccm]

Sooner or later it would have had to be ripped out. You've done a great job of drilling out the rivets. I blame your problems on bad transom design. I've never seen one go all the way to the bottom of the floor before. But hey it's better to do this now rather than have to when you get the boat all fixed up. I like the design and what your going for here; cant wait to see it finished so keep up the good work.
Now only if it could quit raining where I'm at so I could finish prepping my boat for paint.

 

[Kismet]

You know.........


it occurs to me that you maybe might not want to replace the bottom half of the transom with wood, which will (someday) have the same issues.

Gotta be some synthetic...plastic, fiberglass, cutting board-type stuff that would be available that thick and wide, and then you could just put wood up on the top (half/third/whatever).

Glue the two together.


Might work, maybeso?

 

[bobberboy]

So if I kept it 3-4" up from the floor would there be any structural issues? It would be a lot easier because I wouldn't have to deal with the little tabs that are currently screwed to the transom. It would also solve the problem of water being trapped against the transom as it would then have a 1-1/2" channel to drain to the bottom without the of plywood.

 

[Kismet]

bobberboy » Today, 05:57[/url]"]So if I kept it 3-4" up from the floor would there be any structural issues? It would be a lot easier because I wouldn't have to deal with the little tabs that are currently screwed to the transom. It would also solve the problem of water being trapped against the transom as it would then have a 1-1/2" channel to drain to the bottom without the of plywood.

I wasn't thinking of raising it above the floor, just using a different material IN PLACE to prevent future rot.

I'm guessing, but I'd think the floor needs to have that pressure on it for structure solidarity--maintain integrity if hitting a rock or whatever.

But...dunno.

You're doing a nice job. Best wishes.

 

[bobberboy]

.

It's not always easy doing the right thing but about a million rivets later I got the transom out today. It was in surprisingly good shape for being 50 years old. There was about an inch along the bottom that was in pretty rough shape otherwise it was pretty sound. I couldn't have known until I took it out what the side I couldn't see looked like so I guess it's all good. My notion of craftsmanship is doing a good job even where it doesn't show so I guess in the end I had to do what I had to do. I guess it also buys me some bragging rights...I hope.





I couldn't believe how flimsy the boat was once I took off the cast corner brackets at the transom. There was practically no structure to the boat without everything being tied together by the brackets. It's also easy to forget (or hard to imagine) how thin the aluminum really is.

Now I can get the back end cleaned out and solve the problem of draining the water to the center bottom. I have an idea for creating a channel that I'll take pics of when I get to that point. Now it's time to get some plywood.



.

 

[Keystone]

I'm going to have to run up your way and see this once you have it finished.

 

[bobberboy]

Keystone » 8 minutes ago[/url]"]I'm going to have to run up your way and see this once you have it finished.

As I've been at it for four years you needn't hurry!

 

[bobberboy]

.
Got a little work done today. I had to take out the angle brackets between the stringers and the transom to be able to do a good job of cleaning and also to get the new transom in. That added another 12 rivets to the growing number that need to be replaced. I think it's nearly 80 by now. A also found four small holes that I had missed before. They're below the water line of course and are from the mounting and remounting of a depth finder. I got the back half of the new transom cut and fit. The old transom made a poor template so I had to make a cardboard one and ended up recutting to get a good fit. Luckily it needed to be smaller as I couldn't have cut it bigger...



Once in a while I do something smart and that happened last week. I bought a Milwaukee 3/8" reversable close quarters drill. I got it on eBay used and for a good price. It is practically new and I paid less than half of new. I had brought home a right angle drill from a local home store but knew even before I got it home that I wasn't going to be happy with it. The Milwaukee is a good tool and having the angled drill makes the wire brush work so much easier. It's a lot quieter than the regular drill I had been using and it's much easier to hold and see what I'm doing. There is a similar model with a larger paddle style handle but when I was reading the reviews several people mentioned the large paddle handle was too easy to turn on accidentally. The one I got has a large trigger. It's good to have an excuse to buy tools.

 

[bobberboy]

A lot of pictures tonight.

The old transom was 1-1/4" thick so I made the new one from a piece of 3/4" and a piece of 1/2" ACX plywood. I had to make separate templates for each piece - the curve at the back just before the transom went in about 3/4" within the thickness of the transom. Hope that makes sense. You can see on the old transom that the upper third was exposed and visible inside the boat. Because I am going to make the wooden trim from mahogany I wanted this visible part to be mahogany as well.

For the most part what I am doing isn't anything new or special - just laminating up some wood and fitting it. There are a couple of things worth noting and I'll point them out as I go.

The old transom. You can see the exposed parts on the right.



The next pics are cutting and fitting. The back half...





and the bottom of the inside half...





The laminating was straight-forward. Waterproof glue and lots of clamps. I didn't have any clamps with deep enough throats to clamp the recessed edge of the 1/2" plywood so I improvised. I used a bowed 2x4 and clamped it along the recessed edge with the bow facing down. When clamped at the ends the bow puts pressure on the joint along its entire length. And to give additional pressure I also placed some shims between the 2x4 and the plywood. I left the clamps on for 24 hours.



With the shims...the dark line isn't a gap only my pencil line from registering the two pieces before I glued them together.



Step 1 done.



My mahogany board was 3/4" thick and needed to be planed to match the 1/2" plywood...




Next was to glue the mahogany again with waterproof glue and lots of clamps. I ran out of clamps and had to use a vice grip for the last one. As before I didn't have deep enough clamps and spanned the joint with 1x4's and this time cardboard shims to apply pressure.





Step 2 done.



Next I rough cut the mahogany and made a woodshop 101 mistake to begin with. I used a saber saw to cut the mahogany to shape. A saber saw like a circular saw cuts on the up-stroke against the bed of the tool. When cutting from the face or finish side across the grain the blade pulls the wood fibers up. With almost all woods this produces a raggedy edge. The trick is to score along the cut line first with a utility knife and then saw. You can see the difference after I'd remembered what I should have been doing. In this case it probably didn't matter but it will later as I'm fitting more exposed joints together and was a good reminder.





At this point the fussy work began. I filled the edges all around with Bondo then began a lot of work with the belt sander. It took around a dozen fittings before the match to the inside of the hull was good. Once the fit was good I could mark the cut-out to match the aluminum.

You can see the radius at the back where the side and transom meet and the Bondo at the top edge..



Once the cuts were right some final belt sander work was needed to get the angle of the top to match that of the transom-to-boat angle. After some trial and error and fooling around I figured out the angle. It's hard to see on the pic but I clamped a piece of flat stock steel to each side of the transom. The inside one was about 1/4" lower and was the inner, lower edge of the top. I used the belt sander and sanded down until the edges of the steel were shiny and I knew I'd gone far enough. For the curves I used a drum sander on an electric drill and eyeballed it.





And the finished piece...



I'm in the process of coating it with two-part resin - two coats each side and four on the edges. My rivets arrived today but I'm going to give it several days to cure.

Before long I have to make a decision about the floor. I can't make up my mind whether I am going to make a flat floor or follow the curvature of the boat. There is a case to be made for each. The flat floor is easier to work from for the rest of the interior. It also would provide a cavity to run wires and a lot of room for floatation. The curved bottom would lower the overall center of gravity and the passengers would be seated about 5"+or- lower than with a flat floor. I'm sure there are other arguments both ways and I'd appreciate any opinions.

I pulled some strings to show the location of a flat floor.

 

[Kismet]

You got some "craftsman blood" in you. Nice, well-thought out, and patient work is reflected in the end result.

(go for the lower floor.)

=D>

 

[zipperer]

It looks like in the old pictures it had a false floor . That would ad strength and you would need it with 40 horse on it.

 

[bobberboy]

Much of the work of the PO was false so I suppose that could include the floor. The old floor was decomposed to the point that I didn't have to remove the screws until after the floor had been removed. Also, I think a certain amount came out along I70 and I35 on the way home from Denver. I don't know if I have mentioned it but it turns out that all the seams are welded. The chines and spray rails were then riveted over the seams so from the outside it looks like a riveted boat. The USCG plate on the inside rates it for a 40 hp so I am assuming the boat won't come apart at speed. I plan to put a floor back in it, I just don't yet know whether it will be flat or curved.

 

[bobberboy]

I have just a little to add today. I am finally beginning to do some things to put the boat back together. Over the weekend I painted the splash well and stuck it and the new transom in the boat just to get a preview of things to come. I think it's going to look good and I'm getting excited to see some paint being put on the boat rather than taking it off.







I tried this Rust Oleum paint for the inside. Don't have a pic of the finished product but I know you have to put it on pretty heavy in order for the "hammered" affect to work. I'm worried that on the insides it will run down the vertical surfaces because it has to be so thick. I'm not sure yet what I will do.



Part of my decisions for the interior also include what kind of seats to use. I found these used seats for a pretty good price on C'sL over the weekend. They'd be perfect except they require an open interior rather than the cockpits I want to make. The color is perfect. I thought to separate them but don't know if I could do so without ruining them.



Making bench seats similar to these would be an easy project out of mahogany and would be fitting with the vintage of the boat. I think nowadays people expect to have their rears riding on cushioned seats. I could make bench seats and have cushions like throw cushions made but at what $ I don't know. Maybe making bench seats and letting the next owner deal with the cushions would be ok.



I'm not getting much feedback about my dilemmas - appreciate any suggestions, criticisms or insights...