Theoretical Keel Question (Encapsulate a Bolt-on)

[TrentePieds]

@ GrahamHO #14:

Now THERE is a thinking man!!!

With your kind permission, I'll use the method if ever I have to pull my keel bolts :-)

TrentePieds

[Hard Rock Candy]

I have never had a boat with a bolt on keel. I would never own a boat with a bolt on keel. I have no idea why anybody would want to bolt the keel on. I have never heard of a keel coming off of a boat with a keel that was one piece with the Boat.. I think the whole Idea is bad. It sounds like somebody had a bad idea and some other people joined in. This may sound like a rant, but it is just a statement of someone that has 50 years of experience making things out of steel and concrete and fiberglass. In my experience you never make anything that can break off, if you make it solid enough in the first place so that it won't break off. My last boat you could lift it by a cable through a hole in the keel and shake it around upside down and it wouldn't break the keel off. It might not break anything off. Mac

[Jim Cate]

Originally Posted by Hard Rock Candy

I have never had a boat with a bolt on keel. I would never own a boat with a bolt on keel. I have no idea why anybody would want to bolt the keel on. I have never heard of a keel coming off of a boat with a keel that was one piece with the Boat.. I think the whole Idea is bad. It sounds like somebody had a bad idea and some other people joined in. This may sound like a rant, but it is just a statement of someone that has 50 years of experience making things out of steel and concrete and fiberglass. In my experience you never make anything that can break off, if you make it solid enough in the first place so that it won't break off. My last boat you could lift it by a cable through a hole in the keel and shake it around upside down and it wouldn't break the keel off. It might not break anything off. Mac

Yep, it sounds like a rant, Mac, a rant that seems to ignore the literally tens of thousands of bolt on keels happily sailing around the world's oceans without falling off. And lots of those keels are on low cost productuction boats, and even on those, the overwhelming majority don't fail. A well constructed bolt on keel has many advantages over the fiberglass encapsulated type, too, especially for vessels taht spend freezing winters on the hard.

You don't tell us how your absolutely bullet and kryptonite proof keel is constructed. You should do that, for we would be interested in that marvel. And you haven't told us how on your boat that nothing could possibly break off of how your mast is affixed, or your rudder, or your prop. Enquiring mins want to know.

Jim

[GrahamHO]

Originally Posted by minaret

Recently pulled a keel on a Farr built this way (Carrol Marine). I hated it, made it much much more difficult to remove the keel. When I reinstalled it, in collaboration with Farr Design Group, I suggested we install in a more traditional (ie both flexible and removable) fashion. Farr Design heartily concurred.

Works for me. I'm not sure why you want your keel join to be flexible but it's a free world. We had no trouble removing my original keel. I'm glad you have a Farr design which has its origins in New Zealand as a break away from traditional design. Bruce Farr's quarter ton design the original 727 type won the 1/4 ton cup in the 70s. Earlier he had success with 18'skiff designs. Then Bruce Farr moved from NZ to Annapolis. Bruce had originally been influenced by non traditional older NZ designers such as Jim Young and Laurie Davidson whom favoured lighter displacement large dinghy style designs. I remember chatting with Bruce about yachts during a blizzard in a mountain hut in NZ maybe 1970 ish and I did not then realise he was to become a famous designer.

[Hard Rock Candy]

Jim Cate. It does look like a rant. But I have only heard about bolted on keels coming loose. I have never heard about say a Morgan loosing its keel or even having a keel loosen up. I guess I am kind of biased against fin keels in General. When I bought my sail boat I wanted one that would go in fairly shallow water because Most of my sailing was done in shallow water at slow speeds. I think I had my boat up to 7 knots one time. But mostly I moved around at 5 or 6 knots. When I retired I wanted away from any pressures to always go fast. Ive been around boats enough to notice that everywhere Iv'e gone, most of the people that ran aground, had fin keels that stuck down about 6 ft. below the water line. I know that a lot of people enjoy racing there sailboats and I understand that the fin keel is probably faster in most situations. But most of the interesting places to go are, to me, close to land. In fact all the deep water can stay Out at sea for all I care. Ive never gone across a major ocean. Iv'e sailed across the Gulf 7 times. That water was deep enough that I didn't worry about hitting bottom. However because of my ignorance. I ran aground about 15 miles off the north coast of Cuba. No land in sight except down, where it was only three ft deep. Mac

[barnakiel]

You will remove some of the strength of the stub when grinding it off.

BTW I can't see why you want to encapsulate your keel. They either come encapsulated or not and that's that.

b.

[minaret]

Originally Posted by GrahamHO

Works for me. I'm not sure why you want your keel join to be flexible but it's a free world. We had no trouble removing my original keel. I'm glad you have a Farr design which has its origins in New Zealand as a break away from traditional design. Bruce Farr's quarter ton design the original 727 type won the 1/4 ton cup in the 70s. Earlier he had success with 18'skiff designs. Then Bruce Farr moved from NZ to Annapolis. Bruce had originally been influenced by non traditional older NZ designers such as Jim Young and Laurie Davidson whom favoured lighter displacement large dinghy style designs. I remember chatting with Bruce about yachts during a blizzard in a mountain hut in NZ maybe 1970 ish and I did not then realise he was to become a famous designer.

Don't own a Farr, and for my purposes (cruising), wouldn't even consider one. Just a pro who works on a lot of boats.

[minaret]

A few points for folks on this thread:

As a pro, I've seem far more money spent on encapsulated keels than on bolt on. Reasons include-

Cheap ballast used instead of lead. Water intrusion often leads to rust and swelling, which leads to split centerline seams and delaminated bilge laminate. Seen everything from bricks to Pachinko balls used as ballast by reputable manufacturers.


Grounding damage. This is the big one. Ground a bolt on keel boat, and it's retorque the bolts, which probably will not be necessary due to leads ability to absorb impact, fair out the gouges in the lead with epoxy, coat it, and splash. Boats with encapsulated keels are completey different. Usually leads to massive structural fiberglass repair. Shock loads are transferred into stringers and framing, often bulkhead tabbing fails, engines need realignment, etc etc. In short, best to have the dangly bits hanging off the bottom of the boat built of something soft which absorbs shock loads and is easy to repair or even replace.


Water intrusion in encapsulated can freeze during winterization on the hard, splitting the keel.

Encapsulated is IMHO strictly a money saving measure by manufacturers. Lead is expensive, casting keels is expensive, a bolt on must be installed, faired in and coated. All expense for the builder. But it's a much better way to go.


I repair a ton of groundings (charter fleets). Usually a lead keel grounding is 1-2k yard bill. Encapsulated is usually two to ten times that, sometimes more. Have seen boats totaled that I was convinced would have been fine with a bolt on lead ballast keel.

Finally, these remarks do not apply to any other bolt on than 100% lead. Cast iron and lead/iron composites are the worst of both worlds and a total cop out by the builders IMO.

[GrahamHO]

Minaret; absolutely correct. Lead is best unless you have a supply of depleted uranium.
Lead is known for its shock absorbing properties whereas cast iron transmits shock. Lead is about 700 lb /cubic' and cast iron about 450 lb / cubic'. This means that lead ballast is more compact than cast iron so in a keel there is less volume and less drag with lead. This can mean a lower COG for the same draft. Lead can be shaped with an electric plane or surform to tidy up a casting and perhaps shape the top to fit a hull. Keel bolts can be cast in place with a solid lead fin. Lead can be comparatively easily drilled if that is required.

[minaret]

Originally Posted by GrahamHO

Minaret; absolutely correct. Lead is best unless you have a supply of depleted uranium.
Lead is known for its shock absorbing properties whereas cast iron transmits shock. Lead is about 700 lb /cubic' and cast iron about 450 lb / cubic'. This means that lead ballast is more compact than cast iron so in a keel there is less volume and less drag with lead. This can mean a lower COG for the same draft. Lead can be shaped with an electric plane or surform to tidy up a casting and perhaps shape the top to fit a hull. Keel bolts can be cast in place with a solid lead fin. Lead can be comparatively easily drilled if that is required.

Ah, but lead is not as strong as cast iron. Therefore, lead keels generally have a thicker cross section. This is one of the main reasons so many newer boats have cast iron bolt on with a lead bulb. The pursuit of that extra knot of speed leads to compromises I personally think unwise for a serious cruising boat. Or any boat, from a maintenance viewpoint.

[GrahamHO]

Originally Posted by TrentePieds

@ GrahamHO #14:

Now THERE is a thinking man!!!

With your kind permission, I'll use the method if ever I have to pull my keel bolts :-)

TrentePieds

Not my idea but a standard boatbuilding practice in AKL. NZ; A normal hole saw is usually extended with a tube welded in I think in a lathe. No pilot drill is necessary as the bolt guides it.
A sledge hammer on the outside finishes it off with the yacht suspended a couple of inches clear in a travelhoist.

[GrahamHO]

Originally Posted by minaret

Ah, but lead is not as strong as cast iron. Therefore, lead keels generally have a thicker cross section. This is one of the main reasons so many newer boats have cast iron bolt on with a lead bulb. The pursuit of that extra knot of speed leads to compromises I personally think unwise for a serious cruising boat. Or any boat, from a maintenance viewpoint.

Ah, but you simply have long keel bolts cast in. You thread the bottom of each bolt and fit a nut there. The long bolts are like concrete reinforcing.

[GuidoY]

Originally Posted by barnakiel

BTW I can't see why you want to encapsulate your keel.

b.

Just thinking of the best of both worlds, (fully lead + encapsulated & i like the fin keel) but clearly there are pros & cons to each.

The heavy epoxy approach seems good, and similar to the method used in the link posted on p1. Is the epoxy also applied to the threads where they meet the nuts, freezing them in place?

What about the Polbream? Quite a bit of cheating death there. Looks like there was actually no keel stub to speak of, just some kind of cross brace & some bolts. Seems a bit underbuilt for such a high end boat.

Maybe a sectional break away type could be invented for just such an emergency. Lose part but not all and keep the boat upright.

[TrentePieds]

Originally Posted by GrahamHO

Not my idea but a standard boatbuilding practice in AKL. NZ; A normal hole saw is usually extended with a tube welded in I think in a lathe. No pilot drill is necessary as the bolt guides it.
A sledge hammer on the outside finishes it off with the yacht suspended a couple of inches clear in a travelhoist.

Indeed. Nothing wrong with that at all, but use your noggin when you do it.

A friend of mine had a boat in slings off a dragline converted to a crane. The nuts had been removed from the bolts. The bottom of the keel was 2 inches off the deck. He hit the keel exteriorly on the side with an almighty wallop of a sledge. The bolts did what he meant them to do, but the weight coming off the crane permitted the jib boom to rise enuff to let the tops of the bolts clear the bottom of the boat. The keel toppled to HIS side. It didn't do his legs any good at all!

TrentePieds

[minaret]

Originally Posted by TrentePieds

Indeed. Nothing wrong with that at all, but use your noggin when you do it.

A friend of mine had a boat in slings off a dragline converted to a crane. The nuts had been removed from the bolts. The bottom of the keel was 2 inches off the deck. He hit the keel exteriorly on the side with an almighty wallop of a sledge. The bolts did what he meant them to do, but the weight coming off the crane permitted the jib boom to rise enuff to let the tops of the bolts clear the bottom of the boat. The keel toppled to HIS side. It didn't do his legs any good at all!

TrentePieds

No keel cradle is definitely a very big mistake.