The Blue Pearl Sinking

[Scot McPherson]

This whole thread is a good argument for an outboard rudder. If the rudder breaks off, it doesn't open up a thruhull


Scot McPherson
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[DeepFrz]

Actually is a good argument for strongly built boats. Some people (not I) call them "overbuilt". I wonder where that phrase came from?

[ontherocks83]

Originally Posted by DeepFrz

Actually is a good argument for strongly built boats. Some people (not I) call them "overbuilt". I wonder where that phrase came from?

Manufacturers to justify keeping costs down.

[Scot McPherson]

Totally agreed...I know they are frowned upon by the largest majority cause they "dont perform well" but that's why I like buehler designs. I don't care about an extra half a mile an hour, I care about feeling safe in blue water.


Scot McPherson
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[Scot McPherson]

In fact, some time ago in 2002 I read a message from someone who owned a buehler Juno. The insurance inspector told him it was the only boat he'd ever seen that he'd feel comfortable rounding Cape Horn with.


Scot McPherson
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[barnakiel]

If one has to glass things ... is it really a boat build for the job in hand?

Why not get a well built hull in the first place.

A hull where the rudder will NOT go. And in the most unlikely event of a rudder failure (say a severe grounding), the boat will remain watertight and, within the new capacity, safe?

There is no argument for inboard rudders either. All rudders can be built well or poorly.

And then "overbuilt". Good question where the term comes from. My bet is it was cast by people who trust in the 'heavy-equals-strong' politicks.

I think there is no need to overbuild things. A well designed and well built hull and its appendages are strong enough to take whatever the nature throws at them, within the limits of the design exercise.

Mind naval architects do use margins and so there is no reason for overbuilding anything.

Just free floating thoughts, not hard facts in stone.

b.

[Scot McPherson]

If you have a 100ft wall of water approaching, which would you prefer; a built within margins boat, or an overbuilt boat?

The margins make assumptions that such and such a force will never be exceeded. Overbuilt makes the assumption that, they will or could.

This is about risk assessment, and how much risk you are willing to assume. Over engineered is for the risk averse.


Scot McPherson
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[ontherocks83]

Originally Posted by barnakiel

If one has to glass things ... is it really a boat build for the job in hand?

Why not get a well built hull in the first place.

.

Money.

We are saving up for and soon can afford to get a newish modern production boat and slowly put money and time into it to beef it up for what we are planning on doing with it, but can't necessarily afford the up front cost of purchasing a "custom" built boat.

Now I'm sure someone is going to come up with lots of older cheaper options of better built boats from back in the day that will save money and so on and so forth. But that isn't what we want at this point.

[Matt sachs]

Over built....like this? 1/4 inch steel hull well braced, the shaft log has half inch wall thickness, the gudgeon has 1/2 inch wall thickness and sits on a 3/8 plate (has since been welded) supported with a piece of 1/2 inch 50,000 psi steel. My engineering firend/ inspector thinks I could pick up the boat and shake it by the rudder and it not fail...Im NOT going to try it..:-)

[ontherocks83]

Originally Posted by Matt sachs

...Im NOT going to try it..:-)

WIMP

[DeepFrz]

I like the phrase "well built" instead of "over built". Engineers can and do make mistakes.

[kmacdonald]

Not everyone can afford an Oyster and not everyone wants a classic.

[barnakiel]

Originally Posted by Scot McPherson

If you have a 100ft wall of water approaching, which would you prefer; a built within margins boat, or an overbuilt boat?

(...)

I would always chose a well designed and well built design over an overbuilt one.

Overbuilding (too much meat) does NOT guarantee any extra safety. In fact, it is a proof of the builder not knowing that it is in the choice of materials and in proper use of materials, techniques and skills that extra gains are made.

In fact, overbuilding may add to structure's early aging and its premature failure.

So I stand by my well designed&built concept.

I also accept the fact that in vast majority of cases a slightly overbuilt element may add nothing or very little to the risks, as well as that it may actually limit some risks, in some cases.

Of the dozen or so books on boat design I have read, NONE suggested overbuilding as a means towards any end.

I think my favourite passages that relate to this subject are in Offshore Cruising Encyclopedia where Steve Dashew talks on loads and how they are addressed in hulls, rigs and appendages. I believe this is a must read and an eye opener to anybody arguing for overbuilding.

b.

[sailorboy1]

I think for the most part "overbuilt" means the builder didn't/couldn't calculate the forces so threw more material at it hope that it was strong enough. Whether they are right and it is strong enough is completely unknown. Cars from the 60s have a lot more material than modern ones, do you feel they were stronger (if you do then it is pointless to debate it with you).

I just don't really understand all this talk about designing things for loads, but then trying to say it isn't enough. Wonder how some of you could possibly drive you car over a bridge.

[Jimbo485]

Originally Posted by ontherocks83

Now you all are making me want to see if there is a feasible practical way to glass in the compartment my rudder post is in just for peace of mind.

Correct me if I am wrong but I only need to have it be water tight to a bit above the water line and not to the deck right? Obviously factoring in how low it would be sitting with the transom full of water

This is correct. Not hard to do and makes total sense.

All of our thru-hulls, except the water maker intake, are located on the other side of watertight walls that extend higher than water level.

This means that rudder failure, stern or bow collisions or thru-hull failure are all contained and separate from the main internal hull volume but all still accessible for observation or repair.

The effort and cost to design this in to a boat is negligible.