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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > Sailboat Design and Construction
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  #1  
Old 05-10-2008
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It amazes me that they do this.

So often, when I see people working on boats, they make the same mistakes that the manufacturer of the boat made when repairing the boat. Why would you want to do that.

A good example is in one of the recent threads where a hull support in the bilge rusted away because it was made of stainless steel. Why would you want a large chunk of stainless steel in your bilge?

IMHO, it would make far more sense to replace that chunk of stainless with a fiberglass laminate that will not be affected by the water that often is found in the bilge. Also, a steel piece up against the hull, like this piece was, will cause two hard edges that the fiberglass laminate will flex and fatigue against—where a properly installed and designed laminate support will not.


Just because the manufacturer chose to do it a certain way, doesn't always mean that is the right way to do it. Before going about a repair, I think it makes sense to take a look at what other alternatives there are and if any of them make more sense to use.
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  #2  
Old 05-10-2008
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If it is not broke ,don't fix it..If it is broke redesign it...
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Old 05-10-2008
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If it aint broke, don't use it...
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Old 05-12-2008
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Bilge material

This is a very good question that brings up my situation of modifying an original design in either material or structure. I am no naval architect or engineer...I'm about to replace my steel beam at the bilge level with a coated aluminum.

Is the design intent of the original boat spec a concern? Off of the dock, who should make this call...designer has passed on...common sense or local shipwright? Right now, it's a novice me making some important structural decisions.
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Old 05-12-2008
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I wouldn't use aluminum in the bilge, as it is far too vulnerable to galvanic issues if the bilge is wet at all.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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Old 05-13-2008
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I have spent the better part of the last 2 1/2 years doing a restoration of a lower end production boat that I felt had a reasonable enough design, but rather poor execution.
There is a lot of satisfaction for me to put right the places where the original builders chose to save enough to make a profit. Things like minimal tabbing of bulkheads, no sealing of structural plywood members, minimum size on fasteners, and rigging, non sealed holes in a cored deck, etc.
Often the architect had something specific in mind when he drew up the plans but the builder was forced to make a profit in a very competitive world.
The key, and a difficult key to find, is to try to analyse what the designer had in mind and rebuild it that way.
There are many places where that is extremely difficult to do, such as a suspect design or execution of a hull/keel joint, or hull deck joint. At places like that it becomes a question of worth.
Then of course there is that line between having a boat to sail, and having a boat to restore/repair.
Let's face it, even the Hinckley and the Swan's didn't do everything the best way, and let's be realistic, not every boat owner can find the formulas and do the math to plot the scantlings for a boats structural members. Probably less than 5% of boat owners can look at a structure and even hazard a guess about how strong it might be, or even what loadings it might be subject to.
For someone with hand skills, but no formal engineering training it could/should be daunting to change the basic design of a structural component, especially one that affects the safety of the rig or hull, and one that changes the materials involved. I'm not sure that the "That should hold" mentality is in order here.
I do not argue the choice of carbon steel in the bilge, nor do I argue that fiberglass would be a better alternative where corrosion is an obvious issue, but I wonder why the original designer chose to use steel when it would have been easier, and probably less costly to use fiberglass. The steel piece was most likely an outsource for the builder when he had an entire staff of workers skilled in composite layup.
I also have developed considerable caution about people who blithely state that it should be done "this way" with no data, empirical or otherwise to prove the point. I had a professor in university who lectured a course on empirical science who used to talk about the desire to prove a point with no data as " Proof by violent waving of the arms..."

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Old 05-13-2008
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Great follow-up. I'm going to call up a local shipwright and pull him into the full discussion and have him explain the materials as well as the design consideration. I wish Bill Lapworth (SP?), father of the CAL boats was around to email...would be fun to have him chime in.

Thanks Feetup.
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Old 05-13-2008
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Quote:
Originally Posted by NOLAsailing View Post
If it aint broke, don't use it...
If it is broke, fix it better than it was, or suffer multiple failures.

Good post SD, unfortunately your positive rep points have to wait as I have to spread them around some.
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Old 05-16-2008
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Quote:
Originally Posted by chucklesR View Post
If it is broke, fix it better than it was, or suffer multiple failures.

Good post SD, unfortunately your positive rep points have to wait as I have to spread them around some.
I gave him some for you, Chuckles.
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Old 05-16-2008
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Unfortunately, cost is often a consideration... and the customer's long term benefit is ignored in search of profit. I have seen that on many boats, including my own. But when you're repairing a failed structural piece of hardware, I see absolutely no reason to blindly repeat what the manufacturer did. Doing so is taking the easy way out... and often will not yield the optimal results.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
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Still—DON'T READ THAT POST AGAIN.
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