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Old 18-01-2014, 18:05   #421
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pirate re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Oiiii.. got called a 'Whore of the Sea' last year... don't you start.
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Old 18-01-2014, 18:22   #422
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Oiiii.. got called a 'Whore of the Sea' last year... don't you start.
If the rubber fits...........
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Old 18-01-2014, 18:58   #423
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This is just wrong. Cats don't load their rudders anywhere near as much as mono's do.

Because we don't heel, we don't get the massive weather helm and sometimes uncontrollable rounding up tendencies. Because of this, rudders are usually much smaller.

I honestly doubt if many steering systems have been designed with consideration given to the loads possible when the boat is driven backwards at high speed, and the steering at a high angle.

I think that if one were to motor full astern and then suddenly let the steering go to full lock, there are a lot of boats that would suffer damage.

I see your point, but think this is boat model specific. Sounds like these folks didn't have a boat balances as nicely as yours.

Out of curiosity, what composition and size are your rudder stocks?
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Old 18-01-2014, 20:01   #424
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Originally Posted by nimblemotors View Post
With an angle grinder and abrasive disk, I easily cut up an entire sitdown jetski made from 3/8in thick solid fiberglass in about 3-4 hours.

Here is the evidence, and the little 50hp engine prize inside.

Having tools onboard seems as essential as wine and a washing machine when crossing oceans.
Not sure I understand your point here in relation to the thread. The boat had no power, so power tools would have been useless. Also, I don't see how an angle grinder and abrasive disk would have helped them in any way even if they did have power.

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Old 18-01-2014, 20:23   #425
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Re: Alfa 42 "Be Good Too" rescue 300 miles off Cape Henry

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Originally Posted by Palarran View Post
BING BING BING - now I'm thinking the owners insurance company is just going to pay the claim and subrogate the claim back to the manufactures insurance company. It seems like a pretty easy case from the owners perspective, they manufactured a boat that almost killed them and needed to abandon due to the defects.
I really doubt the builder has such a policy. We're not talking Toyota or Honda here. even Fontaine doesn't payout when they have a settlement against them in the US.

Seems to me it was essentially a custom boat built on contract for this owner. He needs to accept most responsibility for items not correctly spec'd.

additionally his insurance company would need to accept responsibility for issuing a policy on a boat that they shouldn't have.
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Old 18-01-2014, 20:47   #426
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Originally Posted by malbert73 View Post
I see your point, but think this is boat model specific. Sounds like these folks didn't have a boat balances as nicely as yours.

Out of curiosity, what composition and size are your rudder stocks?
My Nautitech 40 rudders are probably a similar size and spec. The rudder stocks are 1 1/2" SS tube and the quadrant is attached by through bolt. The emergency tiller fits inside the tube and keys onto the through-bolt.

Perhaps this is also under spec'd but it's probably typical of European standards for production cats.

If you look at the attached photo (serious risk of embarrassment at the visible lack of maintenance) I believe the important difference is that my set-up includes a substantial limit stop (foreground) and you can more or less see in the photo that the limit is set at approx 30deg only. The photo was taken 'hard-over', with a metal rule highlighting the centreline position. I seem to recall that my previous yacht (monohull) had limits set at closer to 45deg but cats use their engines for that sort of tight turning. I'm not going to stray into armchair hydrodynamics, but surely the setting of a conservative limit of the rudder is a key factor in this..
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Old 18-01-2014, 20:57   #427
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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PEOPLE..... Steel is somewhat hard... Stainless Steel is a BAZZILION times harder... Anybody who has worked with both, knows that normal tools (blades/drills/taps) that cut steel like butter become useless waste bin filler when the stainless just mocks them.... Yes, there is plenty of special tooling that cuts stainless, but it takes force, cutting oil, and slow speed POWER...

I once drilled two 5/16" holes through a broken 2" stainless ruddershaft in a fairly large bilge... in minimal 4 foot seas... it took 10+ bits and over 5 HOURS... WITH A POWER DRILL.... The resulting discomfort felt like I had been in a rollover car accident... And I was in extremely good physical condition.
Exactly,.... force and slow speed are critical,....and how are you going to apply FORCE in that situation,...when that force forces you away from your intended object
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Old 18-01-2014, 21:01   #428
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Second I wonder if the so called piercing bows contributed to the fact that they were hit so hard. Would bows with more buoyancy allowed boat to float over the "rogue wave"? Please comment. I am very curious what people think especially about the second question.
Very unlikely that the different bow shapes would react that much different in the 'momentary' rough wave.
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Old 18-01-2014, 21:08   #429
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Very unlikely that the different bow shapes would react that much different in the 'momentary' rough wave.
I would think that the wave must have encountered the whole of the boat (bows and deck and house) in order to impart such a blow as to shove it backwards from a forward speed of 8 knots (if that was really what was happening at the time). The shape of the bows is likely a pretty small factor in a hit like that.

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Old 18-01-2014, 21:33   #430
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Originally Posted by chris in SG View Post
My Nautitech 40 rudders are probably a similar size and spec. The rudder stocks are 1 1/2" SS tube and the quadrant is attached by through bolt. The emergency tiller fits inside the tube and keys onto the through-bolt.

Perhaps this is also under spec'd but it's probably typical of European standards for production cats.
If you were planning a fair bit of offshore cruising in that boat, I think I would be looking at reinforcing that rudder system, particularly in light of this incident. On a cat this size I'd be looking at using minimum 2" shaft, or better yet 2.5-2.75" tube. I think I used a 1 or 1.5 inch solid shaft on our little coastwise 26' Firefly trimaran
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Old 18-01-2014, 21:53   #431
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Re: Alfa 42 "Be Good Too" rescue 300 miles off Cape Henry

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Originally Posted by Palarran View Post
BING BING BING - You win the prize for the correct answer.

Also, I not sure the steering was jammed. If it was, they would have known there was a problem with the rudder before diving on it.

Does anyone else keep thinking about all the other problems they had? One bad starter, one or two bad alternators, malfunctioning generator, etc. Earlier I had said they would probably get a new boat from Alpha, now I'm thinking the owners insurance company is just going to pay the claim and subrogate the claim back to the manufactures insurance company. It seems like a pretty easy case from the owners perspective, they manufactured a boat that almost killed them and needed to abandon due to the defects.
?? They abandoned due to a lack of steering due to a rudder jammed hard over, not because of any of the possible defects. The only real defect we've seen so far that couldn't have been operator error is a leaky window. All else could have been operator error (couldn't get things to charge, then it started charging, burned out a starter motor) or due to being thrown backwards down a wave.

The latter would have damaged many boats. The bad steering design with just a set screw actually would have potentially helped in this situation and didn't cause the problem.
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Old 18-01-2014, 21:57   #432
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Originally Posted by beiland View Post
If you were planning a fair bit of offshore cruising in that boat, I think I would be looking at reinforcing that rudder system, particularly in light of this incident. On a cat this size I'd be looking at using minimum 2" shaft, or better yet 2.5-2.75" tube. I think I used a 1 or 1.5 inch solid shaft on our little coastwise 26' Firefly trimaran
I dont see the point, the nautitech rudder post is build to acomodate 2 bushings , made in plastic if i remember well for that shaft dimensions, 2 inch shaft?? doesnt matter , in case of collision is going to bend anyway, and we talk about to build 2 new rudders, rebuild the rudder posts, no sense... could be maybe good idea to make the bottom half of the rudder sacrificial, in case of collision , bang! the bottom is gone but you have the top ... the gap between the top of the rudder and the bottom hull is just mm , any small bend and is stuck!!!
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Old 18-01-2014, 22:00   #433
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

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Originally Posted by Jim Cate View Post
I would think that the wave must have encountered the whole of the boat (bows and deck and house) in order to impart such a blow as to shove it backwards from a forward speed of 8 knots (if that was really what was happening at the time). The shape of the bows is likely a pretty small factor in a hit like that.

Jim
According to this article they were forereaching at 4-5 knots when they took the hit. They got hit "all across the windows", so yes it seems to have broken right on top of them.
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Old 18-01-2014, 22:22   #434
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

Reading that article. It seems very clear , there wasn't much more they could do

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Old 18-01-2014, 22:46   #435
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re: Alpha 42 "Be Good Too" rescue 300 miles off Cape Henry Merged

Note to all rudder stock designers--I seem to remember from grade school that the strength of tubing in bending is proportional to the second moment of inertia, or

(Do^4-Di^4).

That would say that for wall thickness proportional to diameter, a 3" rudder shaft is 16 times as strong as a 1.5" shaft. Even maintaining the same wall thickness, the 3" shaft is about 10 times as strong.
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