Rig-fall-down proofing a boat

[s vernon]

I was think about the things I might change on my rig/boat to lessen the chance of the rig coming down in a big hit. It would be nice to avoid big hits, but if you are going to enter rodeo regattas you are putting yourself at great risk so best to do what I can to the boat. You feel silly asking for redress when you are in 10th place in the regatta. Anyway...

My list covered the obvious - strong hooks - tape over the mouth of hooks to prevent unhooking when the stays go slack or make the hook mouth very tight. Fuel line type tubing over the clevises. Perhaps a second slightly slack line next to the lower jib stay to keep the rig up if the lower jib stay spectra line fails. New improved 200 lb tube shaped swivels on the stays. Proper swages maybe double on the stays. No plastic covering on braided stays.

One thing that has me puzzled is the best way to keep the mast pin in the hole when I do not use lower lowers. That is a typical point of mast comes down "failure". I guess I need to tie the mast down to the deck or to the mast step somehow. I wonder if anyone has done this and knows of the best/simplest way to do it. Any other suggestions will be appeciated.

The old vertical fin type mast step with a pin sideways thru the mast and mast step is starting to look like a brillliant idea. I do not want to have to change all my boats and rigs tho.

Just as an aside. I wonder how many people realize how weak and eager to go straight in a hit those typical PeKaBe hooks are. They are very soft metal.

Thank you.

Scott

[Nautic12]

have you looked at the New Zealand ec12 site you may find more safe
ideas for keeping your mast intact its called a "stubbie" all 3 rigs
just drop into the "stubbie"also makes rigging and unrigging very easy ,just a thought from NZ

[yachtie]

On my 21 year old boat the mast is keel stepped via a "stubbie" type arrangement. the mast is Bantock Round Groovy and the stub is the next size up same material. With a bit of filing the mast slots down into the "tube" about 75mm (3 inches to you non metric types)
The mast will stay standing with no rigging in any breeze[:D] Makes putting it together reallty simple - just drop into slot and hook up side stays at your leisure. Only disadvantage - can't move mast fore and aft but if you get the positon correct, do you move it much anyway?[8D]

Chris
NZL1 Longtack
&
NZL110 Swept Away

[Ralph Merkle]

Being new to the 12 and still working on my first boat---The first thing that came to mind when I saw the "accepted" way of securing (?) the mast to the deck with a short pin was that this was a very poor design and could be easily improved on during initial build or retrofitted later on with little re-work . Someone must have surely thought of this long ago so I'm not breaking any new ground . Lengthen the mast base dowell to a couple of inches drilling it as deeply as a standard 1/8th in. bit will go . This dowell will go in the base of the mast just as the original but now we've got more "meat" inside the mast . I made up a CA'ed sandwich of two layers of .063 alum surrounding a 3/16ths center layer of bass . this ass'y replaces the original 3/16ths thick (or whatever)"suggested" mount . Shape to suit and drill thru for the mast pin holes as an original mount , picking a bit to give a tight "push-fit" with brass tubing whose ID matches the solid brass OD in the dowell . Water proof the exposed bass wood and Mount this ass'y where the original was to go . Now-- what we are going to do is match drill the deck for as many holes as you choose of those in the new mast mount and press fit 2 in. lengths (or whatever length you choose) of brass tubing in the mount holes . Cut off the brass pin in the dowell to utilize the max length of the tubing . If you did this right the mast isn't going to jump out of the mount and the mount holes arn't going to wallow out with use AND you can easily remove the entire ass'y . Seal the bottom open ends of the tubing with a small dab of silicon or just simply tape over the unused holes on the top of the mount . Use your immagination to modify the mast compression strut , there are lots of ways to do this .

[Larry Ludwig]

All good, and all true... but if you ever do lose a stay, you will rip your entire deck to pieces when that all comes down. Remember the force of the lever (Give me a lever large enough and I will lift the Earth) and you can do enormous damage.

Actually, the little pin on the bottom works quite well as a designed fail point. It is under minimal load compared to the rest of the rig. If you should demast your boat (I had one run over by a Sunfish) you would be looking at massive repairs time and money. In my case, it cost me an 19 cent clip to replace the forestay attachment.

Radio glitch near the dock, the boat runs under and tears the mast off... had that happen too. [:(]

[Ralph Merkle]

Larry What you have said is certainly all valid and true , no argument on my part there . We all have to make choices in the way we do things and I made mine . I didn't expect my idea to be popular (gee--look he's adding unnecessary weight) . It was meant to get folks thinking about a better way to do things . For example . My modeling experience of some 50 plus years told me to never make the deck out of a layer of soft 1/16th balsa (unless the balsa grain was perpendicular to the glass) with soaked light weight glass on both sides unless that assembly was totally supported , for example over a foam surface which really adds strength . Its almost as though the deck built this way serves no purpose other than keeping water out of the hull as it adds little structural strength , might as well use one of the heat shrink covering materials (some class boats do just that) . It sounds good on the surface and gives one the idea that it must be popular because its the lightest way to go but its not . 1/32nd ply as I used is far stronger and is actually lighter per square inch than the glass sandwich if done right . I've seen a lot of collisions with different class boats (12s ,10 rater , Marbleheads ) over the years but have yet to see one where a strike was far enough up the mast (that "lever" thing) or with enough velocity to take down a partially supported mast , obviously I just missed the one strike that could have ruined someones day . I've looked inside an awful lot of boats of all types over the years and have been amazed at some of the poor structural workmanship I've seen . I'll grant you that if you run into a dock because of radio failure or temporary brain lock and take an edge strike well up the mast with all lines down something unpleasant is probably going to happen but thats a very rare risk combination I'm willing to take as trade for not losing a rig in deep water .

[Ralph Merkle]

Something we have forgotten is that nothing in the present rules or the pending re-write precludes simply running the mast THRU the deck and forgetting the mast connection at deck level . Had I not already cut my mast to meet the 72 inch deck measurement and installed the deck thats the way I would have gone . Easy enought to do this installation along with the ability to reposition the mast as before by simply withdrawing and reinserting . This method is common in other classes . Mast water leaks because of the mast weird cross section ? No , thats easy to avoid . Building the additional internal structure would require a new cross member just under the deck and another as low as possible and would not be a brain twister . This would be a relative piece of cake and would add very little additional weight . With this system all the problems of the existing installation just go away .

[Larry Ludwig]

Hi Ralph,

I didn't explain myself well enough... if (some say *when*) you dismast... the pin sticking down into your boat would do the damage as opposed to allowing it to just slip out of place. Many people think that you need a great attachment point of the mast to the deck when really all it needs is to just be held in place and allowed to release (not unlike a skiers binding) to prevent damage. Let the stays do the work for you.

I have a J boat carrying 6,000 sq in of sail and it rides on a mast foot with a 1/8th" diameter pin that extends 1/4" down. No worries mate.

I blew out a Pekabe block and lost the mast. Total damage:

New block.
[:D]

[Larry Ludwig]

Oh if you need a longer spar to keel step your mast we have them on the website for up to 96"... but those grams do add up, and I personally would not do that... but then I stay awake at night counting grams to fall asleep.

If you want to have a friendly contest, I will put up a matching area dimensional piece of my divincell against your 1/32 plywood for strength and weight and we can let Rick West be the judge, just let me know the size.[?]

[Ralph Merkle]

Larry You mentioned "divincel" , think you meant to say "Divinycell" . Couldn't locate any reference to this being available in any thickness less than 1/4 in. at 5 pounds per cubic foot . Where did you find some suitable for a deck ?

[Larry Ludwig]

Well you got me, I typed it in wrong. [:o)]

I am a manufacturer of the EC-12 along with several other hulls, and we use all kinds of materials.

The thickness is depending on how much pressure you put on it. If you go through the autoclave it gets thin in a hurry. Basically, I can create any thickmess I desire.

Just for fun I put a 4" square piece, 1/8th" thick between two supports and put 8 lbs of lead on it and it did not hardly flex. That was all the lead I could fit on it, but if I could have kept stacking it on, I imagine it could have supported 3 times that.

The 4"x4" piece weighed 12 grams which comes out to 108 grams per square foot (about .25 oz per sq foot)[8D]

[Gene Rosson]

Larry;
108 grams is about 2.5 ounces, not 0.25 ounces. I reckon you just moved the decimal place here.

If we are to get into a friendly argument about decks and stiffness, then we should give some attention to simple beam stiffness equations. I= bd^3/3. Yes I know that plate calculations are different from beam calculations but the concept is similar. The moment of inertia varies as the cube of the depth. That'll give us an idea of relative stiffness. I'll go with a rather thick deck and sacrifice some weight if I must. The deck is a pretty important part of the boats structure. If it is stiff, it is an effective diaphragn that helps the boat hold its' shape.

Back to the leverage thing. The mast and rigging exert a considerable twisting force on the hull. All that accursed lead amplifies the problem. A twisted hull aint running on its' designed lines. Well who knows ? Maybe the twisted lines are faster than the intended ones. Meanwhile I vote for a stiff deck which means it can not be thin. Due respect to Ralph, but one thirty second thick ? If the deck pants in the vertical plane then the risk of having the mast undone is greater. I am not sure that the conventional compression post is all that is needed.

[Gene Rosson]

Only a dummy like me speaks before thinking.[:(] I was quick to comment about Larry's decimal place but that was not the problem at all. 109 grams is a tad less than 4 ounces. Not 0.25 or 2.5 ounces. Four ounces is 0.25 <u>pounds </u>. I must apologize for my faux pas quickly, lest I am banned from the discussion group.

[Philip Whitley]

Evening All

I have read the thread and a lot of interesting points are raised. As I'm sure your aware Kiwi myself included are a mad bunch when it comes hanging onto the A rig while the wind increases.

Even though we more than often should have gone down to a B rig, it is very rare to see a boat de-masted. I can only think of two occassions in three years I have seen this.

Most in New Zealand use the stubbie to hold the mast. This system seems to give not only strength to the foot of the mast but also to the entire rig.

Take a look at an example of this system on our class website. http://www.ec12.co.nz/Buildpages.html

Regards Phil