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| Jack Flash/ Mast discussion http://www.hobie.com/au/en/forums/viewtopic.php?f=13&t=8141 |
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| Author: | ncmbm [ Thu Oct 18, 2007 12:38 pm ] |
| Post subject: | Jack Flash/ Mast discussion |
Jack, I read a post where you where talking about your squaretop flexing the comptip. I have the same problem with my main and the spin only exaggerates the problem. I was considering sleeving a solid tip back on as I have one that was cut off to install a comptip. I have talked to several people that believe its possible to do this. What are your thoughts? Unless we get some serious storms on the coast I don't think used Tiger masts will ever be available. |
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| Author: | JACK FLASH [ Thu Oct 18, 2007 1:12 pm ] |
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I like your idea. A peice of any 18 mast would work. I would think though to make it an effective modification you would need a sleeve that is an exact fit into the stock masts profiles, of which I know of none that exist. I would love to know who the mast supplier is for Hobie is so that could just order a custom length spar that all my parts would transfer to, but to date I have not been able to find out. I may consider going aftermarket on the spar. Other than finding an exact fit sleeve I think the idea would work and be cost effective, especially with about a two foot sleeve. |
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| Author: | ncmbm [ Thu Oct 18, 2007 3:48 pm ] |
| Post subject: | |
Jack, I have allready created a sleeve that I used in the lower portion of my mast as it had much corrosion. Took a section of 18 mast and cut off the sail track, fits perfectly. Had to use the services of a machine shop to get it cut properly. As the mast should never bend forward, unless I blow the main with spin up, no material should be required at the track. Can you imagine any stress riser that could occur? I don't believe the mast has much if any bend at that point, if so seems the comptip would break. What else am I not thinking about? |
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| Author: | JACK FLASH [ Thu Oct 18, 2007 5:40 pm ] |
| Post subject: | |
The loads that you did not mention are twisting along the vertical axis, the pull and compression load from the spin. Downhaul is another load source. Side impacts from capsizes should be remembered although I doubt that would be enough to break the joint. I understand your thought process that if the comptip doesn't break then you doubt your splice would, but breaking the comptip is exactly what I am concerned about. I don't think a different mast is going to win me more races, but rather just give me a higher level of peace of mind. Carbon on the other hand would ease my rigging back pains. |
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| Author: | Tom Machette [ Thu Oct 18, 2007 6:14 pm ] |
| Post subject: | |
What about using a inter 20 carbon mast? You could passably outfit that to take the 18 mainsail. Just a thought |
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| Author: | JACK FLASH [ Fri Oct 19, 2007 7:06 am ] |
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I have thought about that. Still have had no luck in finding one though. |
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| Author: | ncmbm [ Fri Oct 19, 2007 8:16 am ] |
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I can find one but the mods necessary to adapt it to the 18 increase the cost beyond reason. The extrusion shape doesn't work with the base of the 18. A base would have to be created. The used mast itself is close to 1k, hard to justify. Extrusions are available but pricey. A new Tiger mast is around $1600 complete. I am not all that concerned about the comptip breaking, the squaretop certainly won't break it. The way my spin is connected puts the load on the entire tip section and doesn't rely on rivets or tangs to keep it attached so not concerned there either. Its performance that I'm chasing and the comptip doesn't help at all. I may take my chances with the sleeve application or just leave it alone until something breaks. Still chasing proper pre-bend for the Tiger main to remove the backwind issue at the luff. |
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| Author: | JACK FLASH [ Fri Oct 19, 2007 11:10 am ] |
| Post subject: | |
Would it be more feasable to change the masts step to match that of the inter 20 or tiger? Than if using Tiger mast the only issue may be shroud and forstay lengths and of course mast lenght if using the Inter 20 mast. |
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| Author: | ncmbm [ Fri Oct 19, 2007 1:42 pm ] |
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I don't see how that could be accomplished without changing the dolphin striker assembly as well. With our curved beams the step wouldn't fit properly and the center support would be too short. I'm afraid that would cause issues that only an engineer would understand. The straight beam conversion is something I looked into in order to meet F18 guidelines. The mod would be complicated and increase the weight of an allready heavy craft. Tiger shrouds are the same as the SX, or close enough. The Tiger bridles are longer and the forestay shorter, I have a Tiger jib on my boat now and it required a 10 hole adjuster attached with the forestay in the top hole of the furler adjuster. My jib clew attaches to the end of the second adjuster to get the proper sheet angle on the jib. I also use a self-tacker for the jib, pretty easy modification. The self-tacker is the bomb and really cleans off the tramp. |
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| Author: | JACK FLASH [ Fri Oct 19, 2007 1:58 pm ] |
| Post subject: | |
I had Charlie Ogletree/Ullman Sails make the sails custom fitted for my boat. I too added the self tacker system from a Tiger and your right, it sure does clean things up and make jibes alot easier. My jib is also full battened so the self tacker is nice on the beach since I can't furl. Correct me if I am wrong but I believe the Tiger mast step is a threaded rod that goes through the cross bar down to the dolphin striker with a ball screwed to the top of it that the mast sits on. What if you removed the factory center bar from the dolphin striker along with the mast base. Drill a hole through the cross bar, and use a custom length stainless threaded dowl with Tiger ball for the mast and you could reuse the cap that goes on the original dolphin striker. A nut and flat washer on each side of the crossbar would ensure that the cross bar was taking the load and not the dolphin striker. This way you could use the factory 18 dolphin striker, minus the rod going the crossbar in the center. This might also eliminate the cracking crossbar issue that I have heard of but never experienced as any additional load would be transfered directly to the dolphin striker rather to the mast base, then the cross member, and the dolphin striker like the factory 18 set up does. |
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| Author: | ncmbm [ Mon Oct 22, 2007 11:43 am ] |
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Jack, That makes perfect sense, wish I had thought of it first. The Tiger mast would attach with no problem as it doesn't use a step. The mast is turned on its side and attaches via a pin to the ball. Could conceivably still use the 18 mast step and bolt with washer below. Need to think about this more but seems more possible than I had previously considered, now to find some used Tiger sticks. |
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| Author: | JACK FLASH [ Mon Oct 22, 2007 1:23 pm ] |
| Post subject: | |
You definatley could not use the 18 mast step/ball assembly. The Tiger mast is dependant on the mast part of the step and the pin being under the ball. In other words it has to be more than a hemisphere. On the Tigers if I am not mistaking the mast step and the pole going to the bottom of the dolphin striker are one in the same piece. I have an extra front cross bar, I may play with this idea before changing my current system. I would love to here from some one on this forum with an engineering base on the structural soundness of this idea. Remember the Tiger uses that flat 1.5 inch bar for a dolphin striker while 18 is that 3/8 diameter bar. I suspect the reason for the differenct is the Tiger dolphin striker takes more of the downward load of the mast while the 18 dolphin striker takes more of the crossbar trying to flex load. |
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| Author: | JACK FLASH [ Mon Oct 22, 2007 1:34 pm ] |
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Hey I have a question for you. When you capsize do you find that your boat always full turtles? Mine does. I figured I had a leaking mast but I cant find a leak in either section. I used a machine that we test evap systems on cars with. It produces smoke and 2 psi of pressure. No smoke from any location. I hate to say it but I am considering adding external flotation to the mast to prevent full turtles as they are race enders by the time you get it back up. |
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| Author: | ncmbm [ Tue Oct 23, 2007 10:44 am ] |
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Jack, I haven't capsized in so long I don't know what it does. I primarily sail in the ocean and have never had a problem with turtleing the boat. We used to flip her over and dive off the upper dagger board. Have also skied on the dagger behind the boat, and surfed. I don't think the boat has capsized since I changed it to the current configuration. Other than a pitchpole I rarely loose control of the boat, and if my crew stays put I will survive a pitchpole as well. I prefer to go out in 15kts + with reasonably seasoned crew or 2 crew members 25kts +. Have come close to rolling it over backwards in big waves this season but thats it. Broke my endpole spin system in a 5 foot swell this summer, like the midpole replacement better anyway. |
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