Manitu's project: Finessa 33

[roverhi]

I'd stuff foam blocks cut to fit in the pukas where the bolts are, fair them to the keel and then glass over. You may want to get at these bolts sometime in the future and blasting out solid resin isn't going to be fun. Wouldn't expect resin to hold the nuts with the torque these bolts will need. The factory did that with some bolts, not large keel bolts, on my current boat and all corroded up and broke when I tried to remove the bolts. Had to grind out the nuts, fair the glass, make up aluminum backing plates and bolt in conventionally.

The keel is going to work. If you make the keel to boat joint out of some non compliant material like fiberglass, it will crack at the joint. Only way to make it work with fiberglass is encapsulate the whole keel with fairly thick laminate that fairs into the glass of the hull. In essence, make it an encapsulated keel. I'd use 5200, LifeCaulk or some other flexible sealant that will stay water tight and not break away from the keel or hull with the inevitable movement of the keel.

[s/v Jedi]

Originally Posted by barnakiel

This over cast iron keel or lead? Or will it work with both metals?

And how many layer of epoxy do you recommend?

Any point going this way if I have no sandblaster here? (I can grind the keel with wire-brush / drill / angle-grinder, etc..

For metals, but steel is tough to scratch unless you really put an effort into it. The idea is that you put wet epoxy into fresh steel scratches without any oxygen getting to it in the mean time. I would only use a hand brush, stainless steel. Don't get one that is too wide, as that limits the pressure you can put onto each bristle.

You can also use etching kits but I would only use that on nice, smooth and new aluminium.

After the first coat and steel brush thing, I wait for it to gel and put on a second coat. Then I fair and then final coat. But when it is smooth already, the two initial coats are good. If you're gonna glass it, put the cloth onto the 2nd layer as it gels, and wet it out with a roller again and again and again and... until the weave is completely filled. I am not patient enough and put a little Cabosil in the epoxy to make it syrup consistency to get there quicker... but first layer on glass must be without filler in order to wet it out properly.

When it cures before you're done, you need to wet sand it or water + Scotchbrite. Get rid of the amine blush.

Originally Posted by roverhi

I'd stuff foam blocks cut to fit in the pukas where the bolts are, fair them to the keel and then glass over. You may want to get at these bolts sometime in the future and blasting out solid resin isn't going to be fun.

I would use foam + cloth too and just deal with it when the time comes for tightening bolts.

I would use a polysulfate sealant (Boatlife LifeCaulk) in the keel-hull joint.

cheers,
Nick.

[SkiprJohn]

Roverhi has a good solution for the "pukas" which means holes that are at the top your keel.
Didn't know if you knew what "pukas" were.
kind regards,

[manitu]

Hi.

If I use epoxy on the steel, I have to keep using epoxy and mat to glass in the keel, right? The rest of the keel is glassed in with aprox 1/4 to 1/8 of an inch.

About the holes.. How about filling the holes with polyurethane up to just below the nuts, then use a strong filler to lock of the nuts? Then then filler and sand them smooth?

I'll read the posts above more carefully when we are finished with the floors. Just a lunch break now!

.manitu

[s/v Jedi]

Originally Posted by manitu

Hi.

If I use epoxy on the steel, I have to keep using epoxy and mat to glass in the keel, right? The rest of the keel is glassed in with aprox 1/4 to 1/8 of an inch.

About the holes.. How about filling the holes with polyurethane up to just below the nuts, then use a strong filler to lock of the nuts? Then then filler and sand them smooth?

I'll read the posts above more carefully when we are finished with the floors. Just a lunch break now!

.manitu

Yes, only use epoxy on the keel. You really only need a little because I assume one layer of cloth is all you put on?

Sure, put the foam in and then epoxy cloth over it, leaving an empty space behind it. Just finish the rest of the skin and let cure, just make sure you remember where the pockets are Just drill a couple of holes through that thin fiberglass skin and use a syringe to inject epoxy. Make that epoxy with high density filler (the ground bones) or if you really can't get that, Cabosil (colloidal silica). Make it catsup consistence and inject and inject till you drop

cheers,
Nick.

[minaret]

Originally Posted by manitu

Hi.

If I use epoxy on the steel, I have to keep using epoxy and mat to glass in the keel, right? The rest of the keel is glassed in with aprox 1/4 to 1/8 of an inch.

About the holes.. How about filling the holes with polyurethane up to just below the nuts, then use a strong filler to lock of the nuts? Then then filler and sand them smooth?

I'll read the posts above more carefully when we are finished with the floors. Just a lunch break now!

.manitu

Don't use matt in an epoxy laminate (unless it's a stitch matt, and then make sure the matt side is always down), just use alternating DB and WR layers. I would definitely glass the keel stub with more than a layer or two of cloth. I would think filling to just below the nuts would be very difficult, pour foam expands unevenly and it can be very hard to judge how much it will expand. But you could easily pour foam it and then remove the top couple of inches of foam with a hacksaw blade by hand, followed by some sanding and a resin pour-preferably Chockfast Orange, which is gauranteed to capture the nuts and not crack out. It was developed to replace steel shims in high end machinery. I use it a lot. Do not apply a resin layer and then let it cure before laminating over it, this is a mistake. You went to lay up right on the first resin layer while it's fully wet, otherwise you are relying on a brittle layer of straight resin between the two laminates. Any neophyte laminator knows better than this. I often will wet out the laminate tapes on a table and roll them up on a "cassette" for easy wet-out and application, but I have big tables and a wet-out machine for this purpose. You should probably wet-out in place. If you use a laminating resin instead of a bonding resin it will all go much quicker and come out nicer. I use Proset by WEST. Peel-ply also helps save labor and time.

[barnakiel]

One question:

Suppose I want not to use glass / mat - can I just roll on more layers of epoxy and then apply anti-foul right over the epoxy? I am not sure what I would gain with glass mat.

Is adding West System 422 (minimizes water absorption) filler to the epoxy a good idea?

Well, that was two ;-)

THX
barnie

[manitu]

Hm a bit unshure now.. The plan was to fill the holes in the keel up to the nuts with plates of PU foam , same as I used in the floors just to save on the amount of filler needed, and make it easier to remove later if needed.

Outside the keel , the plan was fair the filler in the holes smooth, then use vinylester and matt. I was planning to use three layers of glass , one chopped strand , one rowing and finally one chopped strand. The bottom of the keel is still glassed in and OK.

I'll have to research this a little bit more.

.manitu

[manitu]

One question comes to mind.. How much torque on the bolts? The 6 bolts in the middle are 20mm with 32 mm nuts. The two in front and the two rear are 14mm with 22 nuts.

.manitu

[minaret]

Originally Posted by manitu

Hm a bit unshure now.. The plan was to fill the holes in the keel up to the nuts with plates of PU foam , same as I used in the floors just to save on the amount of filler needed, and make it easier to remove later if needed.

Outside the keel , the plan was fair the filler in the holes smooth, then use vinylester and matt. I was planning to use three layers of glass , one chopped strand , one rowing and finally one chopped strand. The bottom of the keel is still glassed in and OK.

I'll have to research this a little bit more.

.manitu

Yes, I just thought using pour foam would be much faster then fitting all those holes with foam blocks and bonding it in. Either way would do.
Lets make sure we're clear on what's happening here. My understanding is that this was an encapsulated keel, ie the fiberglass laminate covered the whole keel. You ground off the laminate to expose the bolt pockets. The bottom portion of the keel is still covered in the original laminate, but the pocket/turn of the bilge/keel stub area needs to be glassed up to match the original laminate which you removed. Is this correct?
If it is, you're laminate needs to match the original laminate schedule which you removed. I seriously doubt that a single cloth will come remotely close to doing this. How much material did you remove when you started grinding? That's how much you need to put back on. The encapsulation is definitely structural, and was probably the only reason you're keel hadn't fallen off with all those rotten floors. Schedule the original laminate back and then count the number of rovings you can see in the layup, you need to match that. Any areas of thick chop matt will need to be built up as well to match the original schedule. I even try to match ply to ply so my roving ply land on the original. This helps with fiber continuity.
Is this correct? Or was the grinding you did at the start just to remove a very thin layer of glass with fairing over? Theres a big difference between the two situations...
It's hard to tell for sure from the one pic of the exterior of the keel ground, but it looks to me like the original laminate may only be 1/4" thick or so over the keel. This won't be too tough to match, but it will certainly take a whole lot more than a lyer of cloth. Grind the lower grind-back line straight, so you can use straight widths of glass, and build back up onto it to match the original thickness. Pretty sure that's what's happening here, but let me know if I'm wrong...

[s/v Jedi]

Originally Posted by minaret

Is this correct? Or was the grinding you did at the start just to remove a very thin layer of glass with fairing over? Theres a big difference between the two situations...

Exactly... I was thinking it was non structural and the keel was bolted-on cast iron without structural glass.

I didn't encounter bolted on keels covered with structural glass before but that must be due to the limited number of boats that I worked on the keels.

cheers,
Nick.

[manitu]

Yeah, you are both right, kinda..
The keel is covered by about 1/4 of an inch with glass BUT no rowing if I'm correct. I removed all wet and lose glass, grinded the glass away until it stuck to the keel.

.manitu

[minaret]

Originally Posted by manitu

Yeah, you are both right, kinda..
The keel is covered by about 1/4 of an inch with glass BUT no rowing if I'm correct. I removed all wet and lose glass, grinded the glass away until it stuck to the keel.

.manitu

Yup, just as I thought. By the time you grind back to a straight line on the keel and schedule the lower laminate back you will be glassing most of the keel up with a 1/4" of laminate. I would grind the hull laminate back a few inches further as well.

[manitu]

I'll double the joint to the hull, to at least 6" maybe 8". And go at least 8" below the holes with the rowing.

But.. Does anybody know how much torque to use on the bolts?

Again. Thanks to all for the help. I'm posting from a android cellphone and cant figure out how to give rep-points from this app for now, but I really do apriciate the help.

.manitu

[s/v Jedi]

Originally Posted by manitu

But.. Does anybody know how much torque to use on the bolts?

my little handyman book has sae sizes for stainless steel only so I'll choose close matched sizes

20mm -> 3/4" 10 tpi 316 stainless, dry torque = 1582 inch/pound-force or 131.8 foot/pound-force or 178.7 Newton-meter

14mm -> 9/16" 12 tpi 316 stainless, dry torque = 753.5 inch/pound-force or 62.79 foot/pound-force or 85.13 Newton-meter

Now STOP a second: you're gonna use a thread lubricant or anti-seize. That changes the torque significantly. For example, if you use WD40, you multiply figures above by 0.8 (so 20% lower torque!). For never-seize, that figure goes down all the way to 0.45

If you post what lubricant you use I can see what comes closest on my list and post the right correction number.

cheers,
Nick.