New Zealand AC72, What I Saw Today

Technical discussion of ARC products
SC15Av8or
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Re: New Zealand AC72, What I Saw Today

Post by SC15Av8or »

What is your choice Grog Man?
Well Bill ....since I am a commoner and one of the many I made my choice. I started 4 years ago with a 1970's era H14T that I put together and learned to rig, sail and repair. There were second hand parts a plenty out there on the web and in a pinch most H16 parts worked on it as well. Thank you Commodore (aka Havliii)
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H14 on Labor Day 004 2.jpg
As my skills in sailing grew I stumbled across this rare derelict along side the road.
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After a season more of growing and learning I stepped it up to its bigger brother.
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All together 3 boats and trailers for less than $10K a third of what you are saying for just one boat. The time spent and experiences priceless. These are the boats the masses have to choose from as the prices are that of a common grog drinker. Main line commoners have to buy our grog and do not need carbon fiber ever where. Just a fast pair of fiber glass hulls, seaway hardware, good clothe and some recycled cans of grog that we have enjoyed at some time after a sailing.

Main line masses drive Ford, Chevy, Toyota and Honda for a reason. Not BMW, Mercedes, Porches. Not even close to Ferrari, Aston Martin and Lamborghini. The way to make this sport more main line is to appeal to those driving the Fords at prices they can afford out of there wallet. Hobie seems to have seen this and still makes the same H16 (fiber glass) with improved fiber glass materials along side a F-18 class boat as well with hulls made of fiber glass. Eleven other boat builder were in the class in 2012 as well. Not sure ARC was one or in the F-16 class either. When you have to limit races to 150 boats due to the fact there are that many competing that says a lot.

All your numbers and formulas can not explain why there are so many of the others boats and so few of the SC's, RC's and ARC's out there. The ones that make any sport that of the many want a good blend of materials and cost savings. I don't care how the builder might justify a higher cost for the same product that gets me from A-B safe and with a bit of fun in between. Simple math I see bottom line price is what the common grog drinker like myself will always look at first and foremost. If we can upgrade later and we are still in the game then maybe. But you got to get us in the game first with out breaking the bank or grog budget.
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Lifes 2 short for cheap GROG
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Bill Roberts
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Re: New Zealand AC72, What I Saw Today

Post by Bill Roberts »

Hey Grogman,
There have been two sailing fatilities in West Palm beach on your cheap H boats. The accidents happened because of the design of the boats.
There was one fatility off Daytona Beach while sailing a NACRA. The boat turned over and pop rivits leak and the boat sank and one person was lost to a shark. The NACRA factory was sued and lost everything and went out of business. Prindel bought the molds.
Pop rivets are cheap ways of attaching hardware. Truss head machine screws cost a little more but they last much longer and don't leak.
Enjoy your SCs.
PS SCs are the only boats, cats, that come from the factory with a righting system. Why is that?
It might be that SCs were designed by a monohull sailor that saw turned over cats out in the ocean that could not be righted by a normal size couple as an insult to the boat buyer and a major safety concern.
Down here in S Florida back in the 70s and 80s there were stories told by H sailors about turning over out in the ocean off West Palm and they could not get the boat up. They spent the night on the boat and the next day off Ft Pierce a power boat saw them and helped them right the boat and they sailed in at Ft pierce. The story ends with a big ha ha ha wasn't that funny, coment by the embarressed sailors.
Actually that happening was not funny. If a squall had come through that night, they might not be here at all or a freighter might have run over them.
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Re: New Zealand AC72, What I Saw Today

Post by Bill Roberts »

{You guys in the skunk works projects did not get it right the first time out the door either. It took years of testing and DEVELOPING to end up with the leaking beauty that finally was the SR71. They even had to design a new fuel (JP-7) that had to be inject with triethylborane for that engine to work right. Though it could only carry enough for 16 starts, relights or after burner light offs cutting into its endurance. }
Hi Pro,
You have your wires crossed a little bit on this stuff. Of course it takes years to advance the state of the art in any field. The leaks you talk about were fuel leaks. The reason there were fuel leaks was because at Mach3+ the environment around the engine was so hot that the connections in the fuel lines were yeilded at cruise due to the high temperature. (Yeilded means the material grew beyond its limits to return to its original demonsions when the forcing function was removed.) When the plane came bask to SLS or anywhere to land and these yeilded fittings came back to real world operating temperatures, cracks opened up in the connecting joints. Many, many, many different types of fittings made of many different types of materials were tested and they all became yeilded at cruise condition and leaked when on the ground. The fittings expanded at cruise and did not leak at cruise.
The TEB is an igniter fluid and is squirted into the burner section of the engine to start the fire, combustion, as the engine is started. One engine start is required per mission. The TEB is not mixed with the fuel. If it were, you would have one very large fire and a destroyed airplane in about one heart beat. A squirt of TEB was also used to light the afterburner. Normally the afterburner was lit one time during the mission. The airplanes were not mission limited for lack of TEB. BTW, TEB stands for tetraethylborane.
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Re: New Zealand AC72, What I Saw Today

Post by SC15Av8or »

Bill the H boat was a great learning boat and helped me to decide if I wanted to stay in the sport. There were lots of spare parts to fix what I might have busted and they were affordable. Rigging, sails and tramps. I am sure there have been a few folks hurt on those and ALL other boat names. Comes with the turf when you want to go fast. There are plenty of stories in our own little group of boats that went over and were not able to right with out some assistance. Comes with the turf. Can't do much about hungry sharks no matter what you were on before you ended up in the water. All I can say is sail in a lake then.

The leaky bird SR71 was exactly that and what I was referring to. As you said it leaked due to fitting having to be made for the temps reached at cruise speeds. However due to the leaks it always had to be refueled and slow down to do so. Thus required another light off. So depending on the range and length and how many refuelings it had to get. Sorry I miss spelled the TEB part and yes that was the nasty stuff.

The SC's have been fun boats Bill and I have been thankful a few times for the righting system that is on them. Much like the world of aviation has done the world of sailing is going through a growth spurt and things will for sure change. I think these two areas are closely related and take from each other. Many limits will be pushed and things will be faster, stronger and lighter. In order for this to happen things might have to look different and there will always be a learning curve to the guys out on the point of these advancements as they are doing things NONE of us on here have ever done. So I will give them a break if they stuff a hull or two as I am sure we have all done that and learned from it, how to prevent it, and how to recover from it.
Lifes 2 short for cheap GROG
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Re: New Zealand AC72, What I Saw Today

Post by Bill Roberts »

Grogman,
The reason there are 1980s SCs still around is because they were built with the best polyester resin and the best fiberglass cloth and the best foam available in the 1980s. You are getting the benefit of high quality materials built into SCs.
Down here in south Florida we sail in the ocean in 2 to 3 ft chop minimum all the time. Treating the hull like a beam: Every time the bow of a hull sticks its nose into a wave, it gets a large upward push. This upward push forces the deck of the boat into compression loads and the keel into tension loads. AS the boat goes over the wave, these loads are relaxed. This is cyclic loading like bending a piece of wire, paper clip, back and forth. In the H design boats these compression loads reach a maximum in the deck just in front of the forward tramp post. In a few years of S. Fl sailing, cyclic loading, , the decks on the H boats delaminate in the area right in front of the front tramp post . By delaminate I mean the inner and outer fiberglass skins pull away from the foam core in an area of roughly 1 ft sq. Now the deck/hull have no strength. Continued sailing will beeak the hull into two pieces. There are no 1980s H boats here in S. Fl that have spent their lives sailing in the ocean. Beach cat sailors here in S. Fl looking for a used H boat have learned to push down on the deck of an H boat just in front of the front tramp post and if the deck is soft, move on, keep looking. The boat with the soft deck is no good. Those cheap construction materials have come home to roost.
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Re: New Zealand AC72, What I Saw Today

Post by Bill Roberts »

The leaky bird SR71 was exactly that and what I was referring to. As you said it leaked due to fitting having to be made for the temps reached at cruise speeds. However due to the leaks it always had to be refueled and slow down to do so. Thus required another light off. So depending on the range and length and how many refuelings it had to get. Sorry I miss spelled the TEB part and yes that was the nasty stuff.

Grogman, I think we should let the SR71 thing go. Relative to the leaky fuel line fittings: There are no fuel line fittings known to man that do not leak after flying a Mach 3+ mission in an SR71. The fittings expand and become "yeilded" when they are very very hot and when they cool off and shrink, they don't come back to original size and they leak. Problem not solved. It is a minor problem.
The leaks are not continuous during the mission and they are not responsible for the refueling. The length of the mission, the range, is responsible for the refueling. The engines are not turned off during refueling and do not require restarting. Refueling is done at the end of a mission and the plane flies back to base easy and slow.
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Re: New Zealand AC72, What I Saw Today

Post by SC15Av8or »

I think we should let the SR71 thing go.
Agreed..... I was referring to inflight refueling after take off though.

In a few years of S. Fl sailing, cyclic loading, , the decks on the H boats delaminate in the area right in front of the front tramp post
Agreed and I thought that was from folks standing out there as well. I am glad I do not have to do the delam check any longer as well. How ever is this the same reason for the SC's failing in the same area?? Just forward of the front cross beam ?? The in and out flexing during hard sailing.

I like the new nick name Bill. It has caught on in my group too !!! :wink: :lol: 8) :D

Honored to have a Bill Roberts handle !!!!
Lifes 2 short for cheap GROG
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Bill Roberts
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Re: New Zealand AC72, What I Saw Today

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Hi Grogman,
All catamarans of all sizes experience the cyclic loading right in front of the main beam when punching through waves. Compression loading down the deck and tension loading down the keel. Compression loading is totally different from tension loading. Tension loading is carried on/by continuous strans of fiberglass and the tension forces tend to make the strans nest together, line up together and stay together. Fiberglass strans are good up to about 100,000 pounds per square inch in tension load carrying ability. Compression: Those same fiberglass strans are carrying compression loads also, and those strans are good up to 100,000 pounds per square inch. But something else slips into the ball game in fiberglass sandwich with foam core loaded in compression, load parallel to the surface. Those fiberglass strans carrying the compression loads now do not naturally want to stay in a staright line under the load. They want to buckle and bow and get out of the way of the compression load or force. When these strans do begin to move out of a straight line or smooth curve, breaking their bond with the resin on a microscop level, it is called crippling. With crippling there is stran movement normal to the load path. What is holding the strans or trying to hold the strans in a straight line????? THE GLUE, THE RESIN!!!! The resin has a max strenght of only 25,000 pounds per square inch. So it is the resin that limits the strength of a part loaded in compression. A column or surface loaded in compression is much weaker than the same part loaded in tension. Now the resin strength is not the whole story yet. The foam plays a role also. The foam holds the resin in place and the resin holds the glass strans in place. If the foam is weaker than the resin, then the delam occurrs at the glue to foam interface. If you ever inspected a H delam, you saw that the glass skin has a very thin layer of foam on it. So it is the foam that is the weak link in the H hull construction method. It is a white polyurathane foam, the same stuff surfboards are made with. SCs use PVC foam which is much stronger and lighter weight than polyurathane foam. PVC foam is also much more expensive than polyurathane foam but it lasts much much longer. There are still 30 year old SC boats sailing very well. They may need new sails and tramps and wires but the fiberglass parts are doing fine. Is that OK Grogman? Do you think that is a good thing?
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Re: New Zealand AC72, What I Saw Today

Post by gahamby »

How about this for a foil kit? This is on a Tornado late'70s-early 80s.
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Re: New Zealand AC72, What I Saw Today

Post by Bill Roberts »

This looks like a the foil system that was used on a boat named Icarius that frequently was in the world championship speed trials held in England in the 1970s and 80s. The boat sailed at speeds in the mid 20s, just a little faster than a stock Tornado. When it could not fly, it was much slower than a stock Tornado. It used Vee foils for the main lifting foils. These are self trimming as they run deeper at lower speeds and present more area to the water and clinb up at higher speeds where less lifting area is needed. The Vee foil is inherently stable, a good thing. The Vee foil is much more draggy than the flat wing foil that we see on Moths and AC72s.
In the picture if we say the highest spray we see is 4ft, the speed of the boat is 16 ft/sec, 11 mph. Just a rough estimate.
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Re: New Zealand AC72, What I Saw Today

Post by gahamby »

Yes Bill, that is the picture from the back jacket cover of "Icarus, the Boat that Flies" by James Grogono. I found the book back in the '90s in Hamilton, Bermuda on a booksellers remainder table. The discussion about the AC 72s and foils in general here prompted me to dig the book out of storage and reread it. It was fascinating to see the early work on sailing foils. Icarus posted a speed record of 28.1 kts.for the B class in1987.
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