I'll acknowledge the elephant in the room...Full keel is dead... ssb is dead...

[Jim Cate]

Since then, I have had two bolt on keels....was never very comfortable with that attachment...

Ahh, but did either one fall off or otherwise misbehave?

I've had three bolt-on fin keels now, and have grounded all t hree of them several times, and at least once on coral heads and one on a rock. The two lead ones needed to have bits of coral dug out and some bog put back in the divots. The steel one only needed the bog in a shallow dent, all accomplished at the next routine slipping.

No leaks, no separation, no immediate haul out for inspection (all the hard groundings were in the woop-woop so no slipway anywhere nearby. A quick dive to ascertain that there was no grievous damage and off we went.

IMO, the worries oft mentioned about the evils of bolt-on keels are really worries about poorly constructed boats, not about the type of keel construction.

Jim

[hpeer]

Jim,

That brings up a good point, if I can express it.

With full keel boats there is less worry of grounding damage due to the inherent deign.

Fin keels MAY be well constructed but also may be fragile. And then you need to know which ones are which.

I had a similar discussion with Bob Perry online. My opinion was, for my sailing “style” and location, I want a boat I can run into a rock at 5 knots with no worry. Bob allowed that for my situation that was OK, but that most boats, most well found Water boats">blue water boats, would not meet that criteria.

And it easy to see here in this forum many folks who are extremely uncomfortable with even a mild grounding and suggest at least a short haul for observation. That may work for the vast majority of cruisers, which may be why full keepers are not popular.

[MicHughV]

I'm a (retired) structural marine engineer by profession...and the bolt on keel approach simply did not (and does not) appeal to me. I know how strong these bolts are, or should be...in tension, in shear, in bending, fatigue issues, corrosion issues, etc....but there is more to it than just the bolts...what type of material is the bolt, the diameter, the thread, how these bolts are imbedded into the keel comes to mind, depth, spacing, number of bolts, what safety factor used, and by what means are they are locked into place, what was the quality control at time of build, etc....and more particularly, the fiberglass hull that it is attached too....how thick, how well reinforced, how well braced and so on....the nuts and washers, thread pattern....

I can also calculate with reasonable accuracy all the forces involved when a boat is grounded, heeled over, etc..

There are recorded cases of these bolt on keels separating from the hull.....

Any visit to a boatyard often sees a bolt on keel having to be re-caulked or rust bleeding from the hull/keel joint, the keel "smile" etc....on my boats with a bolt on keel, the bolts, nuts and backing plate were visibly stained with rust...ok, they were all used boats, so their prior track record was unknown to me......the staining could have come from anywhere...but...from where ???

All these things play on my mind...and for these reasons, my preference is for (a) a steel hull or (b) a full keel...

I know that thousand's of bolt on keels are still bolted on...no argument there....but my preference is as stated above....

When I'm 100's of miles from land, I don't want to be worrying about these things, that is my preference, may not be for others, but is for me

[Saleen411]

Originally Posted by hpeer

Fin keels MAY be well constructed but also may be fragile. And then you need to know which ones are which.

I want a boat I can run into a rock at 5 knots with no worry. Bob allowed that for my situation that was OK, but that most boats, most well found blue water boats, would not meet that criteria.

What about a SHOE? Ed Atkin had one fitted to his Acapulco 40 in New Zealand. Seemed like a BRILLIANT idea!

[Skins]

I have a 30' Peterson, bolted on fin keel, and SSB and I sail offshore. I agree with the refrigeration though. So easy to have a fridge these days with solar panels and a diesel.

Not sure I could handle the handling of a full keel boat although I'm sure it would be less sloppy than mine in a swell. I can go upwind though.

[MicHughV]

a sailboat's motion thru' the water is not linear.....it's up, down, left, right, twisting, turning, bow up, bow down, etc, etc, etc..and it's constant when in motion...24 hrs a day, days at a time....it can be jerky, violent moves, etc, etc,

then throw in a couple of sudden stops....

modern 3D computer modeling has the ability to show all this in motion...in color...with the stress lines clearly depicted at each bolt location...etc..etc..etc...

modern race boats with their fancy blade keels, massive bulbs and foils could not be accomplished without this computing power...not to mention canting keels, etc.....the loads at a hull/keel joint can be incredible....there have been noted failures of these appendages in the round the world racers...

at the same time, you have a mast trying to punch a hole thru' the hole, plus an assortment of rigging loads..

and you have by now, no doubt seen the America's Cup boats, with their massive folding foils ...clipping along at 30 knots...

fatigue becomes an issue....and several other issues...and there is still always an unknown factor...

some people, like me, are simply a belts and braces type of person....I want back up for the back up...

[Pete7]

Originally Posted by hpeer

And it easy to see here in this forum many folks who are extremely uncomfortable with even a mild grounding and suggest at least a short haul for observation. That may work for the vast majority of cruisers, which may be why full keepers are not popular.

We carry a spare bolt on keel just in case

I don't think long keeled yachts are made in Europe anymore. Probably down to the fact that sailing in France and Italy sailing is more like a religion rather than a hobby and they want to go fast, so deep fin keels rule the roost.

Here is a interesting video of a quite ordinary European yacht being run aground repeatedly into a rock breakwater, with little damage.

https://www.youtube.com/watch?v=YIglL5vks4g

[Auspicious]

Originally Posted by Cadence

Amen! Just my opinion, not having unsupported appendages below the waterline scares the hell out of me. A skeg hung rudder on a full keel. Granted speed and up wind ability is sacrificed.

And they don't steer very well. Reverse is a guessing game. They generally roll more than fin keel boats.

Lots of skeg-hung rudders NOT attached to the keel with lovely semi-balanced steering characteristics and still providing rudder protection.

Originally Posted by hpeer

Now according to this author, who was talking about full keels With a filet away forefoot in particular, the hard flat leading edge is there because it creates vorticies which flow aft along the keel and improve the performance compared to a long full keel with a pointy keel. The corners are supposed to be sharp.

I don't remember anything like that in hydrodynamics. Perhaps the author was confused about tip vortex shedding and mitigation such as Kort nozzles and the upturned wing tips on commercial aircraft.

The author may have also been confused about efforts to keep turbulent flow attached.

Originally Posted by MicHughV

a sailboat's motion thru' the water is not linear.....it's up, down, left, right, twisting, turning, bow up, bow down, etc, etc, etc..and it's constant when in motion...24 hrs a day, days at a time....it can be jerky, violent moves, etc, etc,

From an engineering point of heave, surge, sway, pitch, roll, and yaw are generally pretty linear (angle as a function of time being linear for the last three rotational degrees of freedom). Certainly discontinuities in the real world from waves, wind, and running aground. *grin* Good seakeeping characteristics stem (ha!) from much more than keel type - hull design is predominant and efficient foils for appendages are a significant factor.

[hpeer]

Auspicious,

I claim no knowledge, just repeating what I read, probably poorly.

Still the designer was Alan Pape, who is not well known, by who was no slouch. Must be there for a reason.

[Auspicious]

Originally Posted by hpeer

I claim no knowledge, just repeating what I read, probably poorly.

Still the designer was Alan Pape, who is not well known, by who was no slouch. Must be there for a reason.

Not particularly familiar with Alan Pape. Google doesn't return much. Like a lot of self-trained builders their grip on the science and engineering is not always strong. Do you have his CV?

Vortices are generally considered to be bad. There may be a good reason for what he suggests (I can't think of one) but vortices wouldn't be it.

Flat plates are fundamentally inefficient in a flow.

[MicHughV]

It was posted here that poor construction is a likely prime failure point, and I share that view....so many things....if you have 10 bolts, but 1 bolt fails, the other 9 must take up it's load...??? more stress ??
when the keel gets attached to the hull, the nuts are threaded on and tightened...this has the effect of trying to pull the bolt out of the keel...so poor bolt embedded ??? lead is soft.....???
getting all the bolts tightened correctly...and at the same torque....???
sometimes a bolt does not correctly align with a hole and must be bent to fit..???
A poor keel casting may have a bolt very close to the edge of the keel ??

it's possible to google keel design....and see the different approaches used by manufacturers to embed a bolt into a keel...

it's an interesting topic.....for sure...

many years ago, when I built my steel boat, I salvaged an old wood boat that had a cast lead keel shoe (which is what I was after), and which I cut into 3 pieces, 2,000 lbs each for transportation and melted into ingots in a homemade furnace..
As the 2,000 chunk of lead melted it was interesting to see the bolts pop lose...steel has the remarkable ability to " float" in a vat of molten lead..but it was clear that the bolt embedment was "by eye"....
and lo and behold, a steel anvil came floating to the top as well as other odds and ends of steel scrap....I don't think the original keel manufacturer EVER thought anyone would EVER melt down his keel to witness his cheating ways...

nonetheless, this just added fuel to wire in my wish to have an encapsulated lead keel.....

The Beneteau has a steel keel casting...a whole other thing...

[Group9]

OP: I like shiny new stuff.

[Auspicious]

Originally Posted by MicHughV

It was posted here that poor construction is a likely prime failure point, and I share that view....so many things....if you have 10 bolts, but 1 bolt fails, the other 9 must take up it's load...??? more stress ??

Ah. Here I have a story to tell. I can't by any means guarantee that all work is done to this standard but the real pros do.

In Machine Design sophomore year of college we had an assignment to design closure plates for manifolds on an oil tanker. These are 10" or 12" in diameter. Big plates. By this time we'd had a chance to see a good deal of real world solutions in freshman winter work at shipyards. We started getting results, individually with plates too thin and bolt sizes way too small. We compared our results and trooped down to the professor's office. "We know these answers aren't what we see out in the world. Why? What did we do wrong?" The prof, with a grin, told us to go rerun the numbers assuming a ship worker (mostly day ladies) only puts in every other bolt and when he strips a thread on one blows it off. We trundle off and plates got thicker and bolts got bigger. THAT was a learning experience. What could go wrong? How do you design to mitigate laziness and error?

I can't guarantee that Hunter or Bavaria take that approach to keel bolts. They should. Other builders certainly do.

[MicHughV]

ya, I've been involved with a lot of construction work....I also demanded...in fact...made it mandatory that I get to check everything before concrete is poured..'cuz once it's poured, nothing can be seen....contractor's know this....and often "accidentally" pour concrete before I arrive, citing 100 different excuses...I've heard some good 'uns......

glad I am in retirement now...really glad....it plain wore my arse out....

not sure how this all fits in with this thread...but....caveat emptor..buyer beware.... !!

interestingly, I've viewed countless boats with a "broker" in tow....this is usually the only source of information about a boat...wished I had the builder in tow, but this would be an unlikely event...some brokers know their stuff...others...not so much...

some years back, when Hurricane Andrew slammed into Homestead, I had an opportunity to go down there to view the damage. There were barges there, with sunken sailboats stacked like cordwood on them, I was able to get right up on them, being as that I was in a runabout and saw some incredulous thin hulls and other storm damage to keels and rudders as a result of pounding, grounding, sinking, etc...... I should post some pictures....it will make you wonder...

[Argyle38]

Originally Posted by Jolly Roger

I suppose square sails are out.

Well, if you look at the mainsail tops of some high tech racing sleds, they might as well call them gaff rigs.

And bowsprits are all the rage again too.

You just wait, us Downeasters are going to be on top of the racing scene yet!!