Nacra 5.0 mast base casting removal and re-sealing

that's what is was for my 5.2 base

while you want the top half of the mast fully sealed to stop water entering if the boat is on it's side

the lower half of the mast, and base, should be well above the water if the boat goes over

in fact i left some rivets off my base so if any water does get in the mast through condensation etc. it can find it's way out

HUGE MISTAKE NOT SEALING THE ENTIRE MAST !!!!! If for some reason your boat goes turtle, your mast base and anything above it will be under water. NOW YOU WILL HAVE A BIG PROBLEM !!!!

i sail on a small inland lake and have been over several times for reasonable times without the turtling, your mileage may vary

Edited by erice on Jul 01, 2011 - 07:35 AM.

Thanks, I got a fun ride yesterday while soloing and ended up completely turtled after my feet slipped while out on the wire and I swung forward on the boat digging in the bows and, subsequently, pitch poling! When I took down the mast it weighed a TON because it had filled partially with water. The only places I noticed water dripping from was on the diamond wire spreaders and the mast base. So, I need to pull off the mast base, clean up the old silicone and re-install and seal it.

Any and all through mast fittings, including the rivet heads, should be resealed at the beginning of the sailing season, or at least once a year if you are in an all year round sailing season. It will take a great deal less time to reseal the mast than to try and right a boat that has water in the mast. Take a 26 foot stick and put one gallon of water (approx 8 lbs) on one end and try and lift from the other end.

My 5.0 had the old style base. It was riveted on with three rivets. After drilling out the rivets, it just slide off. I put on the captive ball mast base, but it did not fit over the enter base. To seal the mast, I put styrofoam in the base and sealed it with silicon. Did anyone else run into this ? Did you leave the bottom open and seal everything above the base? Did the base of the mast change in later years to account for the new casting shape? Here are the old and new bases.

bh3700 wrote: Did the base of the mast change in later years to account for the new casting shape? Here are the old and new bases.

From your pictures it looks to me like they just eliminated the part of the mast base that covered the sail track, but the mast base still covers up and potentially seals the interior of the mast. That design could make it easier to install things like down-hauls that slide up into the track.

Just guessing based on your pictures.

As Damon said, the extrusion is still the same, the base looks like a different shape, but my understanding is that only the little "pointy end" was removed on the captive base.
You don't need to seal the portion where the old base covered the sail track, only the main section. The new style base should slide into the extrusion, just like the old one came out.
I have one of the lower rivets on that small eye strap left unsealed, with a small plastic "stick" pushed into the hole. I put the stick in while sailing, & pull it out (tie to a string to prevent loss) when done, to allow any water to drain.
Eric, I agree that lying on your side for hours won't sink the boat. What changed my mind was being blown over in 30 mph. As soon as the mast hit the water, about 1' of the sail goes under. The strong wind pushing on the tramp drives the boat quite quickly. The mast/sail is on an angle in the water, & it drives down like a chisel going into butter. The mast does not have enough bouyancy to counteract this. My 5.7 turtled in under 5 seconds.
Luckily, I managed to get it wrestled back on its side, with the mast upwind fairly quickly. Afterwards i realized that any unsealed portion of the lower mast would be underwater while turtled. Even 1 gallon leaking in would now be at the mast head, & righting would be a b.i.t.c.h.
If the mast were to fill, i think it would weigh several hundred lbs, I never want to attempt to rescue that situation, so i sealed the entire mast, & put a float on top to make sure it can't turtle.

With the new base, there were two nice sized holes on each side of the sail track what would keep the mast from been sealed. I needed to seal those two holes. With the new base design, I was wondering if the base of the mast was supposed to be open for draining; however, with even a small chance of a turtling, I'll keep the base sealed as well.

Thanks

Take a small bolt with a o ring and thread it in to the mast just above the base. Totally seal the mast. If you ever turtled and some water gets in from some where when the boat is back upright you can take out the small bolt to let the water out. remember there is about 11psi of pressure 25 feet under water. This can squirt a lot of water in in a small hole.

there were two nice sized holes on each side of the sail track

Were these the holes you refer to? They are for mounting the mast rotation control arm. IIRC the bolt is 5/16", you should be able to go to the USA version of Canadian Tire & find two rubber grommets that will exactly fit that hole. They have a double flange, so they will pop in, the second flange will keep them from going all the way in. They will make an almost watertight seal, but can be popped out for drainage.

Edited by Edchris177 on Jul 02, 2011 - 09:11 AM.

I ran into the large opening on the base of the mast too. I filled it with a load of silicone because it would have let a ton of water into the mast in a very short time as the unsealed space was probably 2 square inches! Anyway, my mast base did have 3 rivets holding it on. One in the front, another was the lower rivet on the cheek block and the third was the lower rivet on the main halyard jam cleat. I removed the cheek block, halyard jam cleat and, with the front rivet already sheared off, the base pulled out relatively easily. I cleaned it up, siliconed everything I could find then reinstalled and sealed everything. No problemo, about 2 hours of work. 24 hours to cure the silicone and I'll be sticking the mast in the pool to check for leaks. I'm definately going to look for a way to open a drain hole on the mast, just in case.

I see what bh3700 is saying, as Damon mentioned, the new style mast base has the piece that would have covered the base of the sail track removed, that would leave 2 small holes on either side of the sail track uncovered. Look closely at pic 1 with old base semi-removed, you can see the inside edge of the sail track, if you draw a straight line from either side of outside edge of mast circumference, it will leave 2 small triangles on either side of sail track uncovered, look at the foam plug inside the mast behind the base, makes a good indicator. Do as flyingfishguy did, seal holes.

turbo

I see what you were talking about now. The extrusion on that 5.0 is slightly different than my '84 5.7.
You can see from the photo that I do not have those 2 small triangles to deal with.
good call pointing that out, anyone else reading the thread may not have noticed those two spots. They would flood the mast in a minute or when turtled.

The first picture of the extrusion with the round bolt rope slot . . . I'm curious if that is an original extrusion from Prindle or someone else, or even Nacra. Nacra has been using the triangular shaped slot extrusion for a long time. Nacra outsourced their extrusions and stocked them in bulk, then built the mast to the order of the boat.

So I suspect that this might have been what the very early extrusion profile was with Nacra. Maybe some of you folks can check your older 5.0's and 5.2's.

When I ordered an extrusion a couple of years ago, I notice that the side wall thickness was thicker than my '90's mast extrusion, resulting in a much stiffer mast section, resulting in a remarkable performance improvement.

I know my 1981 5.2 has the same extrusion as the 5.0 shown above. Had the same problem when I replaced my top casting. Did that same thing as you, removed 3 rivets put sealant on the casing, banged her in and re rivetted. Just filled the voids with sika 281 (similar to 3M 5200).

But it the old mast track did cause a problem when I went to run my main halyard down the track. I found out there was no room, so I'm running it outside the track and that seems to work fine.

I'm thinking they may have changed the extrusion around 1984. Most of the major changes Performance made to the designs prior to 1995 appear to have occured in 1984/85.

D.

This is interesting and something we should document. It appears the new mast base casting matches (and seals) the new(er) mast extrusion but the old(er) extrusions end up with the two gaps.

Now we just need to nail down the model years and spell this all out for future mast base replacers.

Wolfman wrote:
But it the old mast track did cause a problem when I went to run my main halyard down the track. I found out there was no room, so I'm running it outside the track and that seems to work fine.

D.

Dave, I remember when you original posted about running the halyard inside the mast and saying it wouldn't fit. I thought to myself, he must be using a large halyard. Now I see why.

So with all of thIs about sealing the mast...

What about the spreaders on the OLDE 5.2s. Had advice here that said"dont EVEN try to seal THEM.. WONT WORK.. Leave a drain in the bottom of the mast cuz you will never seal the old type of D-wire spreaders.. . What about getting a set of newer swaep back spreaders from a newer 5.2 5.8 or 6.0 so I could seal the whole thing??.. Rigging should be the same.. (STAYS ECT ) Always been a bad speller.. Hope u get the idea Hal

Halliske,
I had the old spreaders on mine and I sealed them with Sika 281. It was messy but worked. The problem is that that straight spreaders like to move a bit. The adhesive sealant applied to the washers and around the bar seemed to work fine.

Now I just did exactly what you suggest. I got some swept speaders off a post 1985 5.7. The mast tang covered the holes perfectly and I bedded the whole thing with Sika 281. No problems sealing at ALL. Rigging doesn't change and I reused my 1 year old diamond wires without a problem. One warning I found out that the stock sails on the 5.2 have a luff that is too long for a high power downhaul!! Especially with a Dacron sail that stretches a bit. I dropped my boom about 6" and I can still downhaul the sail right to the boom without flattening the sail very much. Not sure how to fix that without getting the sail recut. Not sure if I want to because the sail is so nice! I probably need another foot of length. Anyone want to sell me a 5.5, 5.7 or 5.9 mast extrusion and ship it to the great white north?

D.

This is interesting and something we should document.

I posted my photo to my album, with a note regarding the differences.

"As Damon said, the extrusion is still the same, the base looks like a different shape, but my understanding is that only the little "pointy end" was removed on the captive base. "

Do you know if I can adapt this captive ball mast base from N5.7 to my SolCat 18 mast? If not, do you know what might be the closest to? The current system completly sucks, it disconnects during mast stepping so I am planning to improve it. I can fabricate something (got full access to machine shop) from the scratch but it is always easier and cheaper to adapt from prooven design. Any suggestions?

I know this is an old thread, but I recently addressed the situation where the mast base casting leaves two small triangular gaps. I began by cleaning and roughing up the inside of the mast extrusion where the triangles are. I then built a dam out of duct tape and some blue play-doh I stole from my kids.

I then filled the area with West epoxy and flox.

After it dried I trimmed the excess with a saw, ground things the rest of the way with a grinder, and then finished up with 150 grit on a sanding block.

The final result seems much better than the giant boogers of silicone that were there before.

Steve Zicree