General Discussion and Documentation For Apron Replacement : BRACING, FASTENERS,BEDDING, FLOOR FITTING,FRAME REPAIR

[bob mitchell]

     I have been at Wilson's (hull #113, 1967) "on the hard" reconstruction  for exactly a month to the day. Things have moved well along, but I have gotten behind on my documentation, and probably will continue to spend more time working than documenting, so this is kind of a catch all catch up before I forget it all or lose track of the photos. I can not emphsize enough that if you are going to rebuild major portions of your boat you damn well better take a lot of pictures and measurements before and as you tear it up. It was obvious my boat needed a new apron, and now obvious as well that it needs a new stem and forefoot as well. My strategy, since the deadwood was in great shape, was to leave as much in place while I redid floors and apron, and then I would maintain the integrity of the boat when I moved onto the other parts, ie start at the beginning and I won't have to go backwards. Yes, it will be a little work to bolt floors in and out as I repair fames and other tasks, but in the long run I think it is the best way for me. But don't despair for me because I am having a great time!!!!

      GENERAL DESCRIPTION OF APRON AND FASTENERS: The principle role of the apron (the 6 laminated layers of 3/4" plywood that run from the stem to the stern)  is  join the masts and cabin structure to the 6500 pounds of lead that form the ballast keel.  1/2" x 12" bolts come up through the apron and hold the floors to the apron, while 7/8" bronze keel bolts go down through the apron and hold the lead. The apron is the unifying structural pivot that that deals with the huge torques generated by the mast/keel forces. Between the lead keel and the apron is the 5 1/2" wide Douglas Fir deadwood, connected to the apron not only by the keel bolts but 3/8" spikes which have ring shanked ends. These spikes ocurr about every 12-16" and seem to have been put in before the last plywood layer of the apron, or maybe they were plugged - but the heads are typically below the top layer of plywood. (Clyde?)

GALVANIZED SPIKES AND BRONZE KEEL BOLTS. THIS PHOTO SHOWS THE COMPLETE APRON CROSS SECTION, WITH THE TWO BOTTOM BEVELED LAYERS THAT THE PLYWOOD PLANKING NAILS INTO WITH BOAT NAILS. (I USED A 30 DEGREE BEVEL IN MY FIRST 7' SEQUENCE, BUT AT FLOOR 21 IT WAS LESS THAN THAT - CLYDE SAYS IT DOES VARY SOME AND I WOULD NOT DISAGREE)

GALVANIZED SPIKE WITH HEAD AND 12" FLOOR BOLT COMING UP THROUGH APRON. (CARRIAGE BOLT HEAD IS RIGHT BELOW VISIBLE SURFACE BECAUSE THEY WERE COUNTERSUNK THROUGH THE FIRST TWO BEVELED LAYERS OF THE APRON AND THEN PUSHED UP THROUGH THE FLOOR - TWO PER FLOOR, 8 1/2 INCHES APART, CENTER TO CENTER, IF YOU WERE LOOKING DOWN ON THE FLOOR. THIS 8 1/2" SPACING ALLOWED THEM TO STAY OUT OF THE DEADWOOD AREA - THE CARRIAGE BOLT HEADS WERE ABOUT  1 1/4" FROM THE EDGE OF THE UNBEVELED LAYERS)

        In my rebuild I will use 3/8" x 8" hot dipped galvanized lag bolts to replace the spikes. This is basically because when the boat is already built you have limited choices on the order of opearations. When I predrill the holes for the bolts I am considering filling them with wood preservative. After that I will fill them with polyester resin or some alternative to seal the apron plywood.

       The frames of the Newporter were prefabbed and connected to the keel/apron backbone. In the photo below the frames are obviously upside down, and the heavy member at the top is called the "FLOOR". In the next photo the apron is clearly visible as the top layered section, with the deadwood below it, and the space for the lead ballast is obvious.

 BRACING: The reason I give the above two photos is so one can consider what the bracing has to do once the floors and the apron are removed. The basic question is what forces and support do the apron and floors supply, and what bracing configuration will replace those forces until the new apron and floors are back in place. I found the vertical 4x4 s did a good job - they took a lot of the cabin load by going directly from the ground to the cabin roof, and more by cross pieces over to the inside clamp. A 2x8" run outside the boat, screwed to the adjacent 4x4 s (aft to forward), and to the planking, will hold more weight, and prevent inward movement of the frames. But what I like best is that a "spacer" roughly supplying essentially the same frame separating force that the floor supplied, can be put between the two 4x4 s. By varying the length of the spacer you can to some degree vary the separation of the frames (see 2x6 between front two 4x4s in photo). I realize this discussion of bracing is somewhat esoteric, but if you reach the point where you actually need to do it, and have thought about it, the discussion will be relevant.

BEDDING THE APRON:  I read my standard boat construction books on BEDDING. Most were general treatments, stating that that bedding compound is always required between any members that are bolted but not glued together for the purposes of filling the voids so accumulated water cannot cause rot, to waterproof or seal the joint, and to protect from worms or borers. My favorite reference was George Buehler's "Backyard Boatbuilding". He had 14 specific references in his index, and I read everyone of them. You have to realize George is right up my kind of non yachty, blue collar guy who designed and built an incredible number of boats. His choice of bedding material was petroleum based roofing tar. One of his main philosophies is build with what is locally available. He was continually debunking the myth that you have to pay 5 times as much for something because it says it is MARINE.  Clyde has stated that the in the Newporter Dolphinite was originally used for bedding. From my own observations, I would say the bedding did an effective job at isolating the deadwood from the apron in terms of water transfer. After reading all the references and opinions on bedding I concluded there was no obvious best that I could know about, and that a lot of things would work, so I chose my own , called PL PREMIUM POLYURETHANE FLASHING AND ROOF SEALENT, availible from Home depot for $6 OR $7 a tube. Of course, if you want you can buy a 3M product that says Marine on it for 3 or 4 times as much. I have had a fair amount of experience with PL, and continue to be amazed at the quality of their products. Before I bedded the first section of apron I soaked the deadwood with copper napthanate (can't remember exact spelling) Although the photo below shows the first sequence of laminations as a unit, when building I laminated one layer at a time.  Since this was the first sequence I was able to lift it up for a final cleaning before bedding. For the rest of the sequences I will have to bed the first beveled layer right before starting the laminating sequence. Remember, the deadwood has a vertical layer of 3/4" plywood on each side, so the bottom width of the apron starts at 7 to 71/2" and bevels out to about 9 3/8" with a 30 degree bevel, more or less.

FLOOR FITTING: For later frames, from 13 on, there are extra cross pieces above the floors that support the sole of the cabin, and since they don't have to be removed to take out the floors and apron, I did not worry as much about the bracing. But from the lower stem/apron junction to Floor 12, these don't exist and I worried a lot about the bracing. Even so, when I tested the old and the new floors 12 and 13 sat a little above the new apron. I attribute this to the upward cradle and bracing forces. So my strategy was to assume that if the old floor holes lined up with the old bottom frame holes, ie I could reinstall the old floors with no trouble or forcing, then I could use the old, still in place bottom frame holes as a pattern for the new floors, and when the bracing was removed and the cradle adjusted, the new floors would settle right down on the apron. This scenario of course assumes that I have made the new floors identical to the old ones, which is reasonable. AN IMPORTANT POINT -- Don't assume, when using the old floors as patterns, that they were necessarily symetrical. Also, you probably can't just mark the bottom frame bolt holes on the new floors from the old floors, and drill straight through, because the holes in the old floor frames that you are joining the new floors to are drilled at various angles - not necessarily straight through.  I THINK THE MOST IMPORTANT PART OF THIS PROCESS IS TO SAVE THE OLD FLOORS FOR PATTERNS, AND TO LEAVE AS MUCH OF THE FRAMES AND PLANKING IN PLACE (UNTIL THE NEW FLOORS AND APRON ARE INSTALLED) FOR REASSEMBLY DETAILS AND SUPPORT.

Floor 9 is a 1/4 to 5/16" thick metal strap. It had a 1/4 shim on the port bottom frame and 3/8 on the starboard

I adjusted the bracing (spreader) until it fit back perfectly onto the cutoff bolts. After cleaning it up with a wire brush on a my side grinder I sprayed it with galvanizing paint, and then coated it with a thin layer of clear epoxy, I will reinstall it with new 5/16" bolts in the bottom frames, and new 1/2 x 12", epoxy dipped hot dipped galvaized bolts through the apron, using the 1/2" holes in the metal strap to locate my apron holes. After drilling the 1/2" (or 9/16" because of the epoxy) I will countersink a 1 to  1 1/2" hole from the bottom. Probably will plug up those holes with construction adhesive, and pour polyester resin down the hole to seal the apron plywood -A REAL GOAL OF MINE IS TO ENCAPSULATE THE APRON PLYWOOD. I will know how successful I was by how much compression set ocurrs where the keel bolts sit on the top layer of plywood. In the newporters I have looked at I usually see that keel washer/bolt combo a 1/2" or so below the apron top surface. It is worthwhile to look up a definition of "compression set" if you don't know about it.

          Floor 7, which is an original one that I saved, fits perfect. I soaked the bottom frame holes in epoxy and then redrilled them to make sure they were not soft. Redrilling through the epoxy soaked wood was a confidence builder. Floor 8, a new floor, also fits great using the method explained earlier. Floor 9 is the metal strap.

The next floors, 10,11, and 12 form the pocket that the mast step fits in, - and I have not done them yet. All of them, and the mast step as well, are new. Drilling through the mast step, floors, and apron so that they all line up will require some thought. My plan is install floors, drill through mast step sitting in the floor pocket (the floors are notched so that the mast step sits in a pocket formed by the notches) to mark the floor holes, pull out the floors and get the holes started straight on my drill press (standard procedure for all floor bolt holes UPDATE:MAY, 2011, "STANDARD PROCEDURE" FOR DRILLING FLOOR/APRON HOLES IS BOLT THE FLOORS TO FRAMES THEN CLAMP DRILLING GUIDE TO FLOOR IN PLACE AND DRILL), reinstall floors and mast step, and then drill through them and through the apron.. 

 

My almost last comment is that a Harbor Frieght close quarters drill for $30 bucks (or its equivalent) is a necessity.

            FRAME REPAIRS: You might notice in the above picture that the scarfed oak frame tapers towards the bottom - well, I made a mistake that you can avoid. I was concentrating so hard on getting a strong scarph

joint that I did not check to see if the new frame lined up with its mate on the port side.

Fortunately the situation could be remedied by a careful cut along the frame with a skillsaw set at the correct depth, and then a little more work with saw saw and chiesel. This is a really important frame and floor (floor 11) because it sits under the center of the mast step, taking a lot of the compression from the mast, as well as distributing the torque to other parts of the boat, so after I remove the planking/sheathing (which is after the floors and apron are installed) I will come back and add a 1" thick or so oak batten on the forward side, from the apron to the chine.  In general, I have three frame repair processes planned: 1)the usual scarph  2) sistering where needed, 3) a flexible, triangular shaped in cross section, 1" x 1" on the triangle's equal sides, oak batten that will be glued in the corner of existing frames between the frame and the planking, AFTER I have refastened the planking. This will give a brand new, refreshed glue joint between the planking and the frames with minimum effort and maximum return because of the flexibilty of the oakstrips. (until they are glued) As far as how the frames are attached to the apron, or fittied to the apron, I would quote Dave Gerr from "Elements of Boat Strength" on page 100. "The floors and the floors alone transmit the loads from the frames to the keel (and across the boat)." He goes on to clearly explain and defend his statement. Definitely worth a read.

        Once again, I am not claiming to be some errudite boat builder with lots of credentials. Just simply recording what I am finding out about Newporters, and what methods I am using to rebuild mine. I am absolutely convinced, with what I have seen, that any Newporter that has been given reasonable care is  a very strong and able boat.

  

 

 

 

 

 

 

 

[Clyde A. Phillips]

The foregoing is a copy and paste from the second paragraph of Bob’s present report: “These spikes ocurr about every 12-16" and seem to have been put in before the last plywood layer of the apron, or maybe they were plugged - but the heads are typically below the top layer of plywood. (Clyde?)” My name with the question mark seems to be a signal for something from me. Here it is:

First, though the apron was fixed to the deadwood in the shop on the other side of the wall of my shop where I did the plywood scarphing and spar making, I never actually saw the work done. But I can say, because I also made the aprons in my shop, that the apron was completed in one operation, from first layer to last layer. So the heads must have been plugged. What you find is what was done, and I have no insight into it. It is also possible that these spikes were driven in below the upper surface of the apron and the resultant hole filled with some sort of putty, including a thickened polyester resin/hardener mixture.

Remember my standard eveready disclaimer is that what I say today is dragged out of an ancient memory of an old codger, but I stand by those memories until something indicates something better. Also, let me tell all of you that I have a great deal of respect for what Bob is doing. We have been in almost constant email contact and he has both informed me of his plans and received my highly critical remarks. Then after he has done what he wanted to do he follows up with a report of the results. When he comes up against a process with which he has no experience he does test runs on equivalent materials to test the resulting strength and in the meantime gain experience in the process. I have great respect for him and his ways and would say to you to carefully consider what he says. I am confident that he will soon have his Newporter back in first class condition. You can do the same for yours.