Super stiff, rigid and tight...not appropriate for cruising?

[Cheechako]

OP: You bring up many valid points. Each situation is different, every system has weak links. An overall analysis is difficult.
I raced on Cal 40's a bit, they are cool boats but yeah... they are not rigid. I remember trying to beat in some roughish choppy seas, you could see the sides of the hull in the V berth oilcan in and out.
On my medium heavy 44 footer, when I re rigged I put a hydraulic backstay adjuster on, as I wasn't satisfied with the headstay sag prior. The boat was on the edge of hydraulic models to purchase, so I bought the big one. What I found is trying to take the sag out of the roller furling headstay wasn't possible really. I was bending the boat instead! I would take up the adjuster 4" or so and the headstay looked just as sagged as before!
Fibre glass layup is not very rigid on it's own for sure. Not nearly as much as aluminum and aluminum not nearly as rigid as steel.

[Matsubob]

The discussion on shrouds, upgrading to a larger diameter of 1x19, etc., is fascinating. My boat is a 30 foot '82 model Mikawa, and I have been wondering about the shrouds. Even the boat is older, it was heavily damaged in a typhoon and the previous owner wrote it off as a loss. So it has sailed very little, so basically the shrouds have been put under very little sailing stress, with their main function being to keep the mast standing upright. I realize this puts a strain on the rigging, and you can never rule out the effect weathering has on it, including electrolysis, stress cracks in the turnbuckles, etc.
So I have been considering replacing the shrouds and have been wondering going one size up in wire diameter and turnbuckles and toggles. The chainplates seem to be a little large for the current wire size, so I have wondered if there may have been two options.
I understand the argument that heavier wire will stretch less but I tend to agree with Jim, that the heavier wire is only tensioned to what the rig needs, rather than to a percentage of the breaking strength of the thicker wire. I simply want assurance against rigging failure when caught out in heavy conditions! And, to me, the heavier wire can be better counted on to hold the mast in column.
Any ideas or suggestions welcome.

[Stumble]

Originally Posted by Matsubob

The discussion on shrouds, upgrading to a larger diameter of 1x19, etc., is fascinating. My boat is a 30 foot '82 model Mikawa, and I have been wondering about the shrouds. Even the boat is older, it was heavily damaged in a typhoon and the previous owner wrote it off as a loss. So it has sailed very little, so basically the shrouds have been put under very little sailing stress, with their main function being to keep the mast standing upright. I realize this puts a strain on the rigging, and you can never rule out the effect weathering has on it, including electrolysis, stress cracks in the turnbuckles, etc.
So I have been considering replacing the shrouds and have been wondering going one size up in wire diameter and turnbuckles and toggles. The chainplates seem to be a little large for the current wire size, so I have wondered if there may have been two options.
I understand the argument that heavier wire will stretch less but I tend to agree with Jim, that the heavier wire is only tensioned to what the rig needs, rather than to a percentage of the breaking strength of the thicker wire. I simply want assurance against rigging failure when caught out in heavy conditions! And, to me, the heavier wire can be better counted on to hold the mast in column.
Any ideas or suggestions welcome.

Heavier wire does not generally make the system stronger. All rigging loads are typically designed around the RM30 of the boat from the mast to the wires, to the chainplates. Unless you are also going to replace the mast with a heavier section, rebuild the chainplates and build stronger chainplate attachments, it is false economy.

You want the shrouds to break first, you really do. Snapping a shroud is a seriously bad day. But if the Cap shroud breaks there is a fair chance you can quickly tack the boat ease the preassure and limp home with the mast intact. If you don't snap the cap shroud and rip the chainplate out of the boat instead you likely ripped the boat in half.


But fundamentally the maximum load a boat can apply to the shrouds is a very predictable number. It is the same as the RMmax of the hull. You simply cannot apply a higher load to the shrouds than this short of hitting the mast with a bridge. So strength in excess of this number is not just wasted it is actively harmful.

Increase your rig size and a touch a stroke expect to sail 2-3 degrees lower upwind from all the extra Aero drag, expect the boat to heel more and need to be reeled sooner as the extra weight of the wire reduces RM, it lowers AVS since the extra weight in the rig is parasitic to AVS. Expect the boat to pitch and roll more as the high up inertia keeps the boat moving longer... Once the wire I see strong enough, every extra bit is directly harmful to sailing performance so why do it?

If you are that worried about your rig coming down then use the same money and pay for a top down rig inspection by a professional. It's a far better use of the cash.

[nematon785]

To put this into practice come refit time, My primary concern is: do I need to hire a naval architect or an engineer to draw up a plan for beefing up a boat, or is it cool to just start adding stringers, beefing up and adding bulkheads doubling up sizes on backing plates, using heavier chain plates, string up bigger standing rigging, adding support and such to rudder tubes and generally going whole hog on makin her strong and stiff? I don't mind hiring out a good plan, and sticking to it, but is that a waste of money?

"Nothin' too strong ever broke" -Maine Proverb

I can beef up a land based structure easily, add posts, beams trusses anything really, and would typically only hire in an engineer to meet an inspection requirement or to do something architecturally pleasing like knock out a big wall and span her instead or float some stairs and other such nonsense. I don't want to trigger issues in a dynamic structure on a boat by making it imbalanced. I also don't want to go down the road of overthinking it all too much. Out comes the comprimise thing again

I like finding a good groove and flow when sailing, so backing off tensions for that last 5% gain will be a standard operating procedure.

Thanks for your input.

[Stumble]

Originally Posted by nematon785

To put this into practice come refit time, My primary concern is: do I need to hire a naval architect or an engineer to draw up a plan for beefing up a boat, or is it cool to just start adding stringers, beefing up and adding bulkheads doubling up sizes on backing plates, using heavier chain plates, string up bigger standing rigging, adding support and such to rudder tubes and generally going whole hog on makin her strong and stiff? I don't mind hiring out a good plan, and sticking to it, but is that a waste of money?It will cost you a lot of time, money, and agrivation. And right now you have no idea if it is even necessary.

"Nothin' too strong ever broke" -Maine Proverb But build a boat to heavy and it will sink

I can beef up a land based structure easily, add posts, beams trusses anything really, and would typically only hire in an engineer to meet an inspection requirement or to do something architecturally pleasing like knock out a big wall and span her instead or float some stairs and other such nonsense.I doubt you have also never had anyone complain that the house you built them was too heavy. Or made terrible progress to windward because of all the Aero drag. Boats are not houses, if anything they are like cars. Have you ever decided to make a car stronger by welding a steel I-Beam to the roof? I don't want to trigger issues in a dynamic structure on a boat by making it imbalanced. I also don't want to go down the road of overthinking it all too much. Out comes the comprimise thing again

I like finding a good groove and flow when sailing, so backing off tensions for that last 5% gain will be a standard operating procedure.

Thanks for your input.

There are a very small number of boats that were originally built with rigging that was too small, like the GP26. Down the road the manufacturer started specing larger rigging because they cut the tolerances too fine and had problems. But this is not normal, in fact unless it shows up repededly on your particular vessel it can be assumed to just not be an issue. Typically this happened because the rigging was sized for inshore sailing and bouy racing but people wanted to take them coastal cruising and the hulls were overbuilt for other reasons (like use in sailing camp, training programs, or just because).

Harkening back to the car analogy, you could replace the shocks on a SmartCar with the shocks from a F350 diesel dullie pickup truck. And I would certainly agree that the shocks are now stronger. But that doesn't mean you have fixed a problem. There was nothing wrong with the shocks that we're there, but you have added a lot of weight for no good reason and the ride is likely to suffer. It won't make the SmartCar more reliable, just more uncomfortable.

[Dave22q]

Wow, great question. I generally assume marine designers know what they are doing messing with tolerances might not be a good thing. Cost is not always the reason designers make decisions. This is one cruiser who would view a history of serious racing to be a potential negative in evaluating a used boat.

[ramblinrod]

Originally Posted by nematon785

I watched a series about a refit on a Cal 40 recently, and it was done by professionals to a very high level at quite an expense. The refit included quite a lot of racing imptovements, many being structural upgrades. They put in new bulkheads, added stringers, super glassed the tabbing, upgraded chainplates, and stiffened the keel.

On another series a a boat was purchased in very poor condition, and the buyer was beset by all sorts of issues. It was suggested that until the boat was completely refit, to sail it "loose" basically not cranking down on every line, and bearing off rather than pounding to get it where they needed to go. Basically take it easy and don't push things so hard.

While reading Brion Toss book The complete riggers apprentice I began to get a general vibe that many racing based methods of design and rigging introduce incredible loads on lightweight gear to maximize speed, and frequently such boats are driven very hard, pointed as high as possible, and lines tightened to extremes.

This makes me wonder about structural upgrades, and their cascading effects, for example upgrading the size of stays and shrouds. Could this actually have a negative aspect of increasing loads on connecting hardware and bulkheads? If you don't upgrade everything such as bulkhead, tabbing, chainplate, mast, step, turn buckles etc, less give in the larger cable may increase loads?

Another example is stiffening the keel. maybe the "wag" the cal 40 keel is known for is just enough shock absorption to prevent the weak tabbing on the forward bulkheads from popping?

The question is: Can strengthening only a portion of the structure on a boat such as a Cal 40 actual put older and weaker areas at more risk? Is there value in this idea of "sailing loose" and taking it easy on the boat to extend the life of everything? I don't mean slacked standing rigging or slatting sails, just backing off a bit on all our tension and course as a matter of habit when dealing with older more fragile and lower budget cruising?

Lots of great posts but the simple answer is, do not strengthen anything beyond original design in isolation. Consider the impact on the entire boat, and what else will need beefing as a result.

In general terms, most designers aren't stupid, and things are what they are for a pretty good reason.

Beefing something up without considering the whole. How did that usually go for Tim the Toolman Taylor? Errrrrggghhhhh!!!! Errrrrggghhhhh!!!! Errrrrggghhhhh!!!!

[fatherchronica]

Oh, I get it. From the header I thought the question was about personalities.