Fin Keel Strength ?

[neilpride]

Originally Posted by Pete7

This is exactly my point, higher manufacturing costs without a real need have consigned long keel hulls to history unless demand from yachties changes, which is unlikely. So the choice is lots of new or secondhand fin keeled yachts or some manky auld boat (MAB) with a long keel. We have to accept that if you want a second hand but newish yacht in the future it will have either a fin keel or or two hulls.

Pete

Pete the article for jordan yachts say its more expensive for the builder to fit a bolted fin keel, lead moulding keels are expensive , bolts are expensive and the internal grid to acomodate is expensive , when a encapsulated keel is in the hull layup schedule plans , many cavitys can be fill it with raw material , like cement or lead ingots, and covered at the top with plenty of glass , the fact is many builders dont choose encapsulated keels is because the design and the expenses to change the design , is fairly right to say that a perfomance benetau hull with a encapsulated keel can KAPUT the idea and rise the final price based in the design, many hulls come from the mold in one piece this days , is imposible in my eyes maybe im wrong let me know to laminate a encapsulate shell in one piece if is not wide enough, old designs are sometimes 2 split molds glued together after coming form the molds and later filled with lead or cement or raw iron...
Cheers.

[neilpride]

Originally Posted by Freerider

Are keels ever bolted on and encapsulated in fibreglass?

Lifting the keel off is the only thing I'm not going to do before relaunch, so naturally its the only thing i wonder about.

I was thinking if it was also glassed to the hull it would just add to the safety factor.

Dont make any sense to me, why bolt when the weight is covered in fiberglass ?
Stubs are glased to the hull , lead or iron not.

Im tired to see owners glassing the keel joint just to wacht how the crack open again when the boat is in travelift , is fairly expensive to do it right , thats why many choose shortcuts , epoxy in the joint, fiberglass, 5200 outside , etc,.....

[mamaitresse]

I have lurked here for a while...but had to pipe up on this one.

A 747 has a wing span of 70 meters supporting close to 1,000,000 lb (at take off) hanging in the middle. If you are worried about how a fin keel is secured to a yacht...don't get in an airplane.

EDIT: - OK, I know that there is a lot of fuel weight in the wings of an airplane...but there is also weight in a ballasted keel....so you get my point right.

[goboatingnow]

many hulls come from the mold in one piece this days , is imposible in my eyes maybe im wrong let me know to laminate a encapsulate shell in one piece if is not wide enough,

huh, what "many hulls come out in one piece" the practice hasnt changed except that closed mould resin infusion is more common.

Dave

[goboatingnow]

Originally Posted by Pete7
This is exactly my point, higher manufacturing costs without a real need have consigned long keel hulls to history unless demand from yachties changes, which is unlikely. So the choice is lots of new or secondhand fin keeled yachts or some manky auld boat (MAB) with a long keel. We have to accept that if you want a second hand but newish yacht in the future it will have either a fin keel or or two hulls.

This is exactly the crux of it. The fact is that there is simply no demand, while several people may quote a boat in the yard for this keel repair or that ( it is only those that are in the yard). If there was a demand, because buyers felt an overwhelming need not to have fin keels or there was sustained and statistically meaningful evidence that there were problems, then we would see all major manufacturers offer them.

dave

[carstenb]

The really big european yards, beneteau, jeanneau, hansa, dufour, bavaria between them build tens of thousands of fin keel spade rudder yachts per year. These are sailed in high numbers all over the world, including, the Baltic, North sea, English channel, Bay of Biscay and around Scotland. Those areas, for all who don't know are amongst the most challenging sailings areas to be found, unless you go looking for extreme.

Up here, force 7 and 8 is NOT unusual and we sail in it frequently.

And guess what? Only a very few of these production boats lose their keels. How many is a very few? I don't know, but it happens so rarely that experienced sailors up here do not worry about.

You're probably better off worrying about your mast breaking-which happens more often

[mamaitresse]

Originally Posted by goboatingnow

This is exactly the crux of it. The fact is that there is simply no demand, while several people may quote a boat in the yard for this keel repair or that ( it is only those that are in the yard). If there was a demand, because buyers felt an overwhelming need not to have fin keels or there was sustained and statistically meaningful evidence that there were problems, then we would see all major manufacturers offer them.

dave

"no demand"...or is it technology...I refer again to aircraft...there are many debates here about the benefits of GRP or steel or aluminium or (not of) ferro cement hulls. The A380 relies heavily on composite materials to make its massive size light enough to get of the ground...how many followed the Volvo Ocean Race earlier this year. Those guy raced composite material boats at 16+ knots in conditions that most of us wouldn't leave the house in...given, a good few of them broke, in f-ing extreme conditions, but then just slowed down and sailed to the nearest port for repairs....again my point is that the engineering of fin keels is the least of your concerns even in an ocean crossing!!!!

[vtcapo]

Originally Posted by goboatingnow

I have seen encapsulated keels that have minor damage weep water and cause untold hidden problems. Ive seen damage to encapulated keels that required major rework, whereas in a lead bolted on keel, virtually nothing was needed ( didnt look the best cosmetically).Ive seen encapsulated keels weep vast quantities of rusty water from internally corroding ballast.



when an minor impact occurs on the GRP surrounding the ballast, you may have compromised the coating, at least on a fin keel all that happens is a ding in the metal ( if that).


Maintenance on fin keels is no worse then maintenance on other parts of the boat.

The fact is bourne out by the fact that the vast multitude of production boats are using such keels and they do not give trouble on any sort of regular basis.

why why is it that people seem to want to run down perfectly good technology and return us to the model T.

External keels and internal keels all have compromises, like everything on a boat.
Dave

NeilPride and Cheechako know what they are talking about. You apparently can't get your head around this issue.

Manufactureres use externally bolted on ballast not because it is structurally better but because it is CHEAPER.

RT

[goboatingnow]

no demand"...or is it technology

its clearly demand, as if a feature sells, then companies would include it, equally if a feature was proven to be a sustained problem, then it wouldnt remain in the design. ( for example wire halyards, or reel winches).

I refer again to aircraft...there are many debates here about the benefits of GRP or steel or aluminium or (not of) ferro cement hulls. The A380 relies heavily on composite materials to make its massive size light enough

I was involved in providing software solutions , in one case to the aircraft composites sector. The debate versus composites is really over and the only thing preventing the completion of an all composite aircraft is the traditional and well founded conservatism in aircraft design.

Likewise the fleet of RNLI lifeboats now have composite hulls, far better strength to weight ratios.


but I believe we are agreeing with each other as this

engineering of fin keels is the least of your concerns even in an ocean crossing

as I fully agree, they simply dont give trouble and lots of other thing do. Far more likely that your mast will go over the side then the keel fall off.

Dave

[goboatingnow]

NeilPride and Cheechako know what they are talking about. You apparently can't get your head around this issue.

Manufactureres use externally bolted on ballast not because it is structurally better but because it is CHEAPER.

I actually never started on the subject, that it was structurally better, if you can show me repeatable strength and durability tests from a reputable test house I will consider that aspect.

Its clear that all keels are compromises, external keels can be shaped to have better chord and aspect properties, hence more hydrodynamic and provide more lift. Encapsulated keels are more difficult to control resin buildup and are not practical in high aspect designs, GRP isnt structural enough for this.

Then you look at production methodologies and aspects of fin keel design help production efficiencies, which is a good thing. Furthermore it is initially more expensive to engineer and build in external keels, whereas encapsulated keels can have any old crap in them as ballast

BUT, all of that is irrelevant, today virtually everyone uses bolt on keels, few give trouble and as several posters have said, problems will occur elsewhere before you have problems with your keel. Its simply a non event.

Dave

[donradcliffe]

Originally Posted by vtcapo

NeilPride and Cheechako know what they are talking about. You apparently can't get your head around this issue.

Manufactureres use externally bolted on ballast not because it is structurally better but because it is CHEAPER.

RT

Its not because its cheaper, its because it performs so much better. Every boat is a compromise. Just because you want a crab crusher that sails like a sunken log, has to turn on the motor to tack and won't back up under control, not everyone else does.

[daddle]

Originally Posted by vtcapo

NeilPride and Cheechako know what they are talking about. You apparently can't get your head around this issue.

Manufactureres use externally bolted on ballast not because it is structurally better but because it is CHEAPER.

Not so sure bolting on a lead keel is cheaper. But a bolt on is definitely higher performance. Lead is expensive. Structurally encapsulating it significantly reduces the keel's density.

What one "needs to get their head around" is that the issue of bolting a keel on, like aircraft wings, was solved long ago.

Yes, a full keeled boat, or a catamaran, will not be so prone to a keel failure. But neither will a condo.

The load capability of a single one inch bolt in GRP is about 50,000 pounds. Twelve of them is 600,000 pounds. Sounds like it might work to me.

This boat has a cast lead keel bolted to a deep GRP stub. The entire keel is wrapped in a couple of layers of fiberglass cloth for fairing. Elegantly avoids the joint crack issue. With a lead casting that goes up to the hull the best I have seen was a shallow socket, bolts, and the gap filled with something like 5200.

I am comfortable with the risks of a fun keel and rudder. I have been in serious ground contact with such modern boats. Never any significant damage. Forced to sail the alternatives I would likely throw myself over the side. That said, if you fancy sailing in ice, rivers, and coral infested lagoons then by all means...

[neilpride]

Come on, boats are not sold by their keels, how many new potential buyers know how well or bad is build the boat, many dont know a **** if the hull ticknes is 5 or 3 mm, and many dont bother if their keel is bolt on or not, or if the liner is glued properly or not , there is things in a boat like the keel design and construction that need to be build it like the wings of a A380 , i mean a failure in a wing for sure send the plane to ground killing everybody, a failure in a keel can kill crew sleeping in the bunks , as i say before from the builder perspective dont make any diference in expenses to design the dam thing with a proper stub and grid to bolt the keel , why many choose to bolt that 7000 pound thing to a 6 mm glass hull without stub and have peace of mind,,, ask J boats or Bavaria .

Yes if the mast fail , is down thats it, maybe can kill someone in deck to , but a failing keel is GAME OVER , and sometimes with casualties, im not saying the keel is going to fail when new or just by coincidence, but if after groundings and collisions the owner dont inspect the keel well and make the apropiate repairs is playing roulette russe, enough is said to the owner of the Etap 38i , you are putting you and your crew at risk in the way back to europe if you dont fix this thing properly and forget this tiny patches of fiberglass here and there,
Boatyards are full of keel problems around , just here we have 3 , the other 2 have 5 or 6 projects on keels to, i wonder how many new buyers are asking to the builder for hull cutouts samples from trhu hull installation?

For the OP, fin keel strenght rely in the hull structure , if a fin keel fail due bolt shearing is a owner fault for not replace bolts in time or inspect the bolts before.
I never hear of a keel failing due bolt failure , maybe someone fail, i dont know, but with enough bolts the keel is safe, all depend in the design and construction , a Amel with 22 holding the keel can loose 2 and keep going and a flat 2 inches fin with 6 bolts and losing 2 can fail, who know.

Looking at the reports of failures mosts incidents end with the structure falling apart or be riped from the boat , this bitch market is cruel , but well welcome to the future of mass production hulls and keels.

[mamaitresse]

Originally Posted by goboatingnow

.. Far more likely that your mast will go over the side then the keel fall off..

Exactly...although loosing a keel is far more serious, loosing a mast by for example getting rolled is far more likely..although given the number of ocean crossing is still relatively uncommon.

They say that flying is safer than driving..I suspect that boating is less safe than either but maybe that is due to intoxicated-redneck-go-fast-boaters.

[carstenb]

Originally Posted by mamaitresse

Exactly...although loosing a keel is far more serious, loosing a mast by for example getting rolled is far more likely..although given the number of ocean crossing is still relatively uncommon.

They say that flying is safer than driving..I suspect that boating is less safe than either but maybe that is due to intoxicated-redneck-go-fast-boaters.

Actually sailing is safer. Go look at Beth and Evans Home Page They have a page that shows the relative risks of various activities. Bluewater sailing is safer than riding a bicycle, or swimming, or anything except golf.

So don't worry about your keel dropping off. Worry about driving your car down to the marina.