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Sea-Skiff with 2 cracked ribs

Framing, planking and fairing. Repair, or reconstruction. If it's hull related, you'll find it here.

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Fleetwood
Posts: 9
Joined: Sat Mar 28, 2009 2:26 pm

Sea-Skiff with 2 cracked ribs

Post by Fleetwood » Wed Aug 01, 2018 11:51 am

My 1963 24' S-S sportsman utility started to leak profusely. I checked under the port floorboards and saw that there were 2 cracked ribs directly under the port front seat. Difficult area to access without removing the entire seat/floorboards. The 2 screws that were into these ribs vibrated loose and were lost. The seam opened up and hence the leak. Mid-season repairs are needed, so I plan to use either some Marine-Tex epoxy and new SS screws to tighten up the seam and fasten into the ribs (several inches away from the cracked area ) My plan B is to use 5200 sealant fast set to fill the open seam and refasten the plank with SS screws.
Off season repair is to remove the seat entirely to access the ribs. I will cut out the cracked sections, make new oak rib filler stock and epoxy bond in place. After paint stripping the 2 ribs, I will fabricate new carbon fiber channels to cover a long portion of the weakened rib area and epoxy in place. Then I will through bolt/nut the planks into the channels and do the same for the planks in the open areas. Do you have any suggestions or ideas that may help?

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Bilge Rat
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Joined: Thu Jul 16, 2015 4:02 pm

Re: Sea-Skiff with 2 cracked ribs

Post by Bilge Rat » Mon Aug 06, 2018 3:18 pm

Your repair logic sounds good, however I'm not certain on how the carbon fiber channel will work out. The area of the broken ribs is where your boat rides when up on plane and it will take a pounding as you cruise along. This is a common problem. I have a 25 foot Lyman, similar construction to your Sea Skiff and when I was restoring her and replacing keel and bottom planks, I found cracked ribs in this same area. I was able to sister new white oak ribs and used 5200 and bronze machine screws to secure them in a similar fashion to what you proposed. I would suggest not using the fast set 5200 as you need all the time available to line all of this up and permanently secure it before it cures.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

Fleetwood
Posts: 9
Joined: Sat Mar 28, 2009 2:26 pm

Re: Sea-Skiff with 2 cracked ribs

Post by Fleetwood » Wed Jul 17, 2019 3:35 pm

I was able to do a more definitive repair on the broken ribs (2) and cracked ribs (2) in the past two months. Working in the parkway by my summer home on 4 day long weekends. I returned to my home and shop to fabricate the needed woodwork and gather the tools for the next couple steps. For the defective ribs, I cut out sections on a 45 degree angle with a Multimaster tool. I fabricated the rib replacement pieces with 1-1/4 " wide white oak strips that were milled to 5/32" . I used Glass Magic epoxy adhesive to laminate up 5 thicknesses and clamped them firmly together for curing. The wood laminates were then thickness sanded to the exact match of the ribs in the boat. I had previously paint stripped, washed with alcohol, and sanded the ribs and the adjacent stringer surfaces. I trial cut the rib replacement sections and then fitted the laminated rib pieces to be placed adjacent to the ribs (8) to have better coverage. Each section of overlapped planks was given three through bolt/washer/nuts to hold the planks firmly together. I could not trust the clenched copper nails and rivets as they were stress expanded. I embedded the sistered rib sections using more Glass Magic epoxy. The through bolts were placed over the area of overlapping planks. I placed the nuts in counterbored recesses and then cut the bolts off flush, filled the counterbore with Marine-Tex epoxy. For additional strength, I embedded 2 layers of carbon fiber 3" ribbon over each rib section with two vertical sides and a double thickness main overlay. To transfer the stresses of these ribs to the stringers, I made 1-3/4" x 1-3/4 "x 3" oak blocks custom fitted to the mating surfaces and embedded with Glass Magic epoxy and long screws. After the epoxy had set, I smoothed off the surfaces , applied a primer, then bilge color paint to the whole eight rib section between the stringers. During the sea trials there was no leaking in that repaired section. I spent another full day replacing the floorboards and seat components.

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