When to Refasten?

[Mark Cattell]

I have a 1966 45' Stephens motoryacht, carvel planked mahogany on oak, silicon bronze screws, glued seams. When last hauled three years ago for survey, pulled apx. 20 fastenings and maybe four (20%) were spinners. Surveyor said monitor situation, consider refastening in future.

So my question is at what point should I pull the trigger on refastening? I understand that can't refasten multiple times without weakening the overall structure, so don't want to start the clock until I have to (especially on a fairly lightly built Stephens, she only displaces apx. 25,000 lbs). However, don't want to wait too long either.

If we pull 100 more screws and find that sure enough 20% spin (either b/c of wasting of the screws or softening of the wood around them), should I begin to refasten, or is 20% spinner acceptable for a lightly used vessel?

Thanks in advance for sharing your opinions...

[Jack Heinlen]

Are you seeing indications of movement in the structure? Bulkheads no longer tight, undue leaking, stuff like that? The fact that some of the sample of fastenings pulled wrung off is a bit worrisome, but even brand new bronze is fairly easy to break. What did they, and the ones that came out, look like?

[Mark Cattell]

No movenment, leaking etc. on the boat. The problem screws didn't break, they just spun without backing out, and the rest of them had only minor deterioration. However, they ARE 40 years old, will need to replaced at some point. Question is, now or a few years from now? It doesn't seem like a good idea to wait until start seeing structural issues before addressing, but on the other hand I keep hearing "if it ain't broke"...

[Disco Bay]

Trefethen and many others suggest a "rolling refastening" working an arbitrary amount or area of the hull, refastening each time the hull is pulled from the water.

If you pull out each winter I would think this a fine idea to attack a relatively easy, but time consuming task.

For instance, if you were to section the boat off in quarters, working from garboards up, you could have the entire hull refastened in four years. Be sure only to work in small sections, though, as to not end up w/ a sprung strake.

I'd think this would take the worry out of the issue for you, while keeping this mighty task somewhat painless.

~mjb~

[ 11-08-2004, 07:29 PM: Message edited by: Disco Bay ]

[Jack Heinlen]

What is the framing material? Oak, but what kind? It sounds, just shooting from the hip, that the fastenings are okay.

[ 11-08-2004, 07:40 PM: Message edited by: Jack Heinlen ]

[BRobinson]

Typically spinners are broken screws. They spin because the head is no longer attached to the threads.

[cbob]

Mark, One big part of such a refastening is removing the A F to find the bungs, and there is an assumption you haul for the winter, each year? I did a similar job, fwd. half and aft half, 2 years apart on a 1958 L 36, mostly spinners. If you're going out the Gate or up the Delta makes a difference in the pucker factor. That said, when the heads are shot and you can't get the spinners out with a 1/8 drill nesteled into the slot on the spinners, going forward, i.e. clockwise, after loosened, its too late to do it right. The longer you wait the more spinners. How long do you expect to keep the boat? You may have to go up a size on the screws, 12 to 14 or such, so be sure you have these on hand, good prices at Jamestown, Hamilton and the like, or a wholesale account at Fasco.
Also, as you remove these, think what a horrible task this would have been if slotted screws had not been used, and think of the next refgastening, hopefully slotted screws again.
You should be able to get some good local advice and help as needed from Hank Easom, the Arquez School, SCWB (Spaulding Center), and Classic Yacht, Bill Linderman.
There is a refastening article a while back in WB on how to grind crescents inscrewdriver blades to get these spinners spinning, very helpfull. Luck, cbob

[Mark Cattell]

The vessel is 1 1/16" mahogany planks on 1 1/4" x 1 3/4" steam bent oak frames, 10" centers, don't know the species of oak. Currently fastened w/ original 2" #12 silicon bronze screws. Owned her for about 10 years now, plan to keep forever so want to do what's in long term best interest of the vessel.

What's driving this is that looks like I need to wood the bottom (too many coats of antifouling paint have built up over the years and it's flaking) regardless, so seems logical time to address the fasteners if needed. We only haul her every two years-18 months not annually.

I'm on fence between "If it ain't broke, don't fix it" and "It's gonna break at some point in time, so let's be proactive". While I don't want to begin refastening if no need, my understanding is that the difference in size between #12 and #14 screws isn't that great, so might be very little down side to doing the forward 25% or so of the boat even if theoretically might not NEED to for another few years. At least that's the direction I'm leaning, especially as plan to wood bottom this haulout anyway.

What do you think? Again, thanks to everyone for their time and insight.

[ 11-09-2004, 02:51 AM: Message edited by: Mark Cattell ]

[Thad]

If most screws are noticeably degraded but you can still get many out, now is the time -- especially as you plan to strip the bottom. If you wait you will have to fight to get every screw out. Better to do it now while they are still holding some.

[sdowney717]

Most of your screws are spinning because they are wasted and the threads are gone. Those screws are not holding anything. Wasted screws means water is getting in and eventually can cause angel hair rot if the water is salty. That is where weepage of salt water dries out as crytals on the wood cutting and shredding the fibers. it is a steadily destructive process and can eventually shred and destroy wood to a deep level. Also fresh water from rain may have been running down the inside of the planks finding its way between frames and planks and to the screw holes. Then you will find that new screws wont hold due to the frame holes rotted out.

Here is an excellent article about how to survey a wood hull and pulls no punches but lays it all out for you.

http://www.yachtsurvey.com/Wood.htm

[sdowney717]

Also use square drive screws such as McFeely screws.
I have been replanking my own boat and it is so easy compared to a slotted screw. A number 14 screw uses a number 3 driver bit and I have broken none of the screws and only stripped a couple out. This is how I found out my frames had to be drilled out and epoxy plugged. Put in a new screw and it wont grab but just spin. I have also replaced 14 frames in the aft section starboard side and anticipate the same on the port side.

[sdowney717]

Also existing fasteners need to be pulled and the holes reused when refastening. If you simply run new screws into newly bored holes you are weakening the planks. Just imagine if you keep on drilling holes across a plank eventually it would crack in half. Now imagine the forces working on a plank in a seaway, wracking and twisting across a plank frame interface where a bunch of new holes have been drilled.

[BillP]

Fasteners typically waste first around shaft logs, rudder boxes, etc. If those areas are good, chances are the rest of the boat is better.

Good luck pulling 40 yr old screws out. That may work for newer boats and small skiffs but it is unrealistic to think you will get them out by grabbing the shank and turning. Why? If the heads spin off then the shanks are probably hourglassed at the plank to frame joint too. That means they will break there and leave the tip in the frame. You can't get them out without destroying the plank. Even if the screws are good they can be impossible to remove.

If it was my boat...refasten by screw or ringed nail. Drill between the existing fasteners and set which ever you prefer. Screws are best. The additional hole(s) may weaken the plank so stay out of hurricanes or the central North Atlantic ocean in winters. Otherwise the boat will do most anything a sane individual will want to do. Then I'd WEST the bottom. Did it on 3 sailboats over 20 yrs ago...32', 35' & 42'. The oldest is still sailing fine and does the Bahamas every yr. If you want the boat to last forever do WEST or a full glass sheath like A. Vaistes(sp)does.

[Elco's]

Sdowny, great advice. Thats how I did the "ChasE". How is your Egg comming?

[sdowney717]

I am almost done refastening the starboard side. Today I fit the rudder post in the new strut log and put on 2 more planks. I am using a light duty 4 ton car jack to push the planks tight against the frames and also its tough to wedge them over at the same time. This jack has been the perfect tool. Its a floor jack style with a nice cup on the end.
Since I am on my own with this project, I end up tying one end up at the stern using twine and work down from the but blocks. I have 2 drills going, one drills the new hole, the other runs in the screw.

I wish there was an easy demolition technique I could use to remove the bottom planks on the other side. Many screws are bad but enough will hold that I have to check each one. I spent a lot of time cleaning up the old planks and making sure they were good. I even had them in the house out of the rain for a few weeks. My garage is an absolute disaster and hardly has room to move around.
I plan on rescrewing up to the waterline.