pvb
Well-Known Member
More rubbish!
Keel/Rudder design
- Thread starter coopec
- Start date
More rubbish!
rogerthebodger
Well-Known Member
Yes I have read the full report and seen the boat when it was recovered and agree with that last statement (not knowing the design specification)
My view is the the manager of production should have been charged with culpable homicide (manslaughter in the UK) but accountability has not been good in South Africa of late.
coopec
N/A
What Lies Beneath
So what can you expect when you run aground? It's quite likely that eventually you will. Boat design and build have everything to do with damage when it comes to groundings. Let's start with sailboats. As new sailboat designs evolve, they are made from lighter materials, which results in a higher proportion of damage. Simply stated, the more we're making keels thinner to go faster, the higher the rate for damage there is. It's a matter of the geometry involved. Thinner, deeper keels that strike objects tend to have the aft end of the keel pushed up into the hull, while the leading edge is pulled down in somewhat of an equal but opposite reaction. Both actions can and often do result in hull damage
Sailing Toward Damage
From my experiences as a surveyor, let me break down some typical grounding scenarios, starting with a hard grounding on a solid reef or ledge. With the rugged bottom of a full keel with heavy laminate, you may get lucky and bounce off. In many cases like that, a haulout and external repair of the damaged area is all that is needed. On occasion, there may be damage to ballast or laminate, but rarely does the damage become a structural game-ender.
This is not the case for the lighter, faster, and deeper keelboats discussed earlier
What Happens When You Run Aground And How To Avoid It - BoatUS Magazine
So what can you expect when you run aground? It's quite likely that eventually you will. Boat design and build have everything to do with damage when it comes to groundings. Let's start with sailboats. As new sailboat designs evolve, they are made from lighter materials, which results in a higher proportion of damage. Simply stated, the more we're making keels thinner to go faster, the higher the rate for damage there is. It's a matter of the geometry involved. Thinner, deeper keels that strike objects tend to have the aft end of the keel pushed up into the hull, while the leading edge is pulled down in somewhat of an equal but opposite reaction. Both actions can and often do result in hull damage
Sailing Toward Damage
From my experiences as a surveyor, let me break down some typical grounding scenarios, starting with a hard grounding on a solid reef or ledge. With the rugged bottom of a full keel with heavy laminate, you may get lucky and bounce off. In many cases like that, a haulout and external repair of the damaged area is all that is needed. On occasion, there may be damage to ballast or laminate, but rarely does the damage become a structural game-ender.
This is not the case for the lighter, faster, and deeper keelboats discussed earlier
What Happens When You Run Aground And How To Avoid It - BoatUS Magazine
pvb
Well-Known Member
Yes, bolted fin keel with 2m draft. Keels are best fitted in factory conditions; it's a skilled process. There are YouTube videos of Bavaria's production process which show how the keels are fitted, with laser alignment.
Keel problems on European-built boats which are exported to the US have been reported, because the boats are shipped without the keel fitted and then the local importer/dealer does the fitting.
PaulRainbow
Well-Known Member
Absolutely ! Mine weighs around 10 t and has been sitting on her keel, when out of the water, for the last 40 years.
pvb
Well-Known Member
Yes, that's a tragedy, but an avoidable one. The boat was badly-built, didn't meet specifications, and had been badly maintained. In normal circumstances, as everyone except coopec knows, fin keels don't simply drop off unless there's been some damage.
pvb
Well-Known Member
No, that's not a fair equation where it's also been shown that many of those might only be sailed a few fair days a year.
coopec's keel will be in no danger of falling off then, if it spends another 20 years sitting in his garden!
Hallberg-Rassy
Well-Known Member
Which boat? Which kind of keel?
I know a guy who runs a second hand tyre shop ...
rogerthebodger
Well-Known Member
You can buy second hand tyres on the side of the road but I wouldn't no even for one of my trailers.
Rappey
Well-Known Member
I often see long keel with skeg hung rudder mentioned ? Is this people getting long fin confused with long keel? Not sure why any designer would sacrifice the rudder protection of a keel by remotely placing a skeg hung.
Whilst I see a figure of 2 out of 100, 000 keel losses mentioned , what about unreported keel losses? This whole debate only seems to base " facts" on recorded loses.
I know of a few around portsmouth harbour where the boats have sank due to keel problems and end up scrapped so go unreported as a keel problem.
One was a bilge keel where a keel fell off , the boat sunk at anchor (unnatended) and is now marked on the charts as a wreck.
Then we have a fair number of boats that have an issue but get it repaired before the problem becomes a disaster, again undocumented.
Could it be that many boats don't have keel issues as they never go anywhere unless it's a nice day?
The above is all speculation as obtaining any figures is next to impossible
Whilst I see a figure of 2 out of 100, 000 keel losses mentioned , what about unreported keel losses? This whole debate only seems to base " facts" on recorded loses.
I know of a few around portsmouth harbour where the boats have sank due to keel problems and end up scrapped so go unreported as a keel problem.
One was a bilge keel where a keel fell off , the boat sunk at anchor (unnatended) and is now marked on the charts as a wreck.
Then we have a fair number of boats that have an issue but get it repaired before the problem becomes a disaster, again undocumented.
Could it be that many boats don't have keel issues as they never go anywhere unless it's a nice day?
The above is all speculation as obtaining any figures is next to impossible
Bobc
Well-Known Member
or could it be that they are perfectly safe when well built and properly maintained.
dunedin
Well-Known Member
So is this now the replacement for the Brent Swain “only steel boats are suitable for blue water cruising” thread?
(The OP didn’t keep to his statement way back that it was his “last post”)
(The OP didn’t keep to his statement way back that it was his “last post”)
geem
Well-Known Member
I think the ‘properly maintained‘ bit is the key. How many have hit something and never bothered to drop the keel and check for damage? I suspect that there are many that don't bother to do this that possibly get future problems or possibly just damage that goes unseen.
Rappey
Well-Known Member
I'm sure they are perfectly safe when maintained but that does gloss over all the boats that have had "maintenance" on the keels due to issues and therefore excludes them from the overall picture.
RJJ
Well-Known Member
Coopec said it was his last post, several posts ago.
The reason this is an issue, as I said, is this poorly-judged rumour has potential to affect the value of our boats. The facts don't come close to supporting the sweeping statement made; it's appropriate to accept that or provide more significant evidence.
The fact is that boats are over-engineered. It's like some saying "you have to have a keel-stepped mast; keel-stepped is stronger". Well, yes, the mast is supported in a different way, but a deck-stepped mast may have different rigging and spreaders to get to exactly the same strength.
Long keel boats have other weaknesses; older boats have other weaknesses, all boats have pros and cons. Since he's unable to prove his assertions about production boats, coopec doesn't have to agree with us, but what he should do is...what he said he would do, and pipe down.
NormanS
Well-Known Member
What are the weaknesses that long keel boats have?
Bobc
Well-Known Member
Reversing them for a start ;-)
rogerthebodger
Well-Known Member
My previous boat was a full length keel and I had no issue revering. The issue I had was turning in a tight space which I had to do as my mooring had a narrow gap between my finger and the one opposite. Buy directional stability can be an advantage in some sea condition.
The truth is that all designs whatever that are have pros and cons as you very quickly learn as an Engineering Designer. The trick is to take advantages of the pros and mitigate the negative points of the cons. (design for the purpose intended) racing boats or cruising boats a racer/cruising boat will have compromises as the design must have comprises due to the different requirements. In the same way a different materials have pros and cons and a purchaser must decide which waiting he places on which material or design for the purchasers desired use.
This is like cars you would not by a Ferrari to go off road or a 4x4 Landrover for a track day .
Bobc
Well-Known Member
but you could equally drive across Europe in a Ford. You don't NEED to have a 4x4 to do it.
In the same way that you can equally sail across the Atlantic is an AWB
