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About samc99us

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    Annapolis, MD

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  1. samc99us

    Retrofit Composite Chainplates

    Do you have a photo? I'm curious as this sounds like a good approach to chainplates on A class catamarans. Downside is when the SK99 chafes how do you replace the chainplate?
  2. samc99us

    Retrofit Composite Chainplates

    This one has my brain spinning due to the inaccuracies in the statement!!!!!! First of all, carbon and high grade epoxy have very similar elongation before failure, so that statement is pretty false. Its when you start trying to pair materials with subpar resins that this becomes an issue. Generally speaking polyester is crap (and in this particular case for a secondary bond SHOULD NOT BE USED). Good vinylesters and epoxies perform virtually identically; epoxy has the advantage of near infinite shelf life and the ability to cure in less than ideal conditions. Vinylester is less expensive and has the ability to cure at different rates depending on mix ratio so is a good choice in a production environment. Second of all, GRP type composite structures are almost entirely deflection driven structures, not strength driven. As the article states, glass is strong enough in tension, but there is compression to deal with and carbon is much better there. Further, carbon on average has an elastic modulus that is 4x greater than glass. Effectively you need 4x less carbon than glass to fabricate a panel with the same deflection. In practice its not quite as good as epoxy makes up >40% of the laminate, so we generally say half, i.e 80gsm of carbon has equivalent stiffness to a layer of 160gsm glass when laminated. This stiffness issue is why you see modern race boats and even performance cruisers using a high amount of carbon in their structures. Often these are sized based on flexural requirements with the exception of say the beams on a performance cat which are typically designed in modern FEA programs and their structure iterated. Still, due to the principals of beam bending, a high modulus carbon beam will way 1/3rd less than the equivalent standard modulus carbon beam, on average, for the same strength and stiffness. The trade off to carbon is all this stiffness means the structure can be a tad brittle. The other trade off when building high performance composite structures is you really want the fibers aligned with the loads; most folks quickly get into trouble as its not always easy to visualize the load path and often you have incorrect fiber orientation which quickly reduces the strength of the structure by an order of magnitude (check uni carbon in the 90 degree plane, its basically useless).
  3. samc99us


    Isabel was also a 2 when she came ashore but several days prior had been a Cat 5 with the strongest recorded winds (233 mph) on record for an Atlantic hurricane. My point here is once a storm reaches the size and intensity of a Cat 4 or 5 storm, even if the wind speed reduces to Cat 2/3 status prior to or near landfall it is still a major hurricane and appropriate caution should be taken. Most of eastern NC is low lying and large parts of I-95 flood in heavy storms; I would get out now or risk not being able to evacuate at all.
  4. samc99us

    Gunboat 68

    Greenflash, Thank you for the detailed explanation. I totally get why you would go this way, my point was that you can build it all in one shot contrary to longy's belief. Beautiful boat and I hope she meets the weight targets!!
  5. samc99us

    Gunboat 68

    Umm, please explain? The molds split along the centerline so I don't really see how the bow shape makes much, if any difference? Tons of beachcat and monohulls built with reverse shear on the bow everyday...
  6. samc99us

    C-Class Little Cup news

    These things are wicked even in non foiling mode. Wouldn't want to sail them in a ton of chop however....
  7. samc99us

    curved foil bearings

    I don't think there is too much info out there on that. The Nacra 17 bearings are acetal. The foiling A-Cat bearings vary, one of the better solutions I've seen used PVC tubes as the lower bearing (1" section floating into 1.25" section hard mounted). DNA had issues with 3D printed lower bearings failing so that is basically out. For a big boat I would go with carbon for the top and bottom bearings, even if you are looking at a swap able bearing solution. Little else outside of titanium or high grade (17-4PH) stainless is going to give you the required load capability.
  8. samc99us

    NASS race Annapolis to Oxford 9/8

    Half the beach cat fleet didn't make it to the start as a serious squall came through at Thomas Point on the way up with gusts recorded to 29kts. I saw at least one other Galesville based boat turn around. It took us at least 5 tries to tack at that point with the breaking swell. We ended up doing the race, ended up second across the line 2 minutes behind the Farr 400. Decided to trailer back instead of sailing yesterday which was the smart call given the poor visibility and pretty nasty forecast. Now time for hurricane prep....
  9. samc99us

    Farrier bought by Daedalus

    Sailabout you may consider visiting the google and do some research on the Farrier/Corsair history. I'm no Corsair expert but Ian left there specifically because of the type of problems you are dealing with. Short story there is Corsair management wouldn't build to Ians detailed engineering/design plans because it was too costly/time consuming so they did it their way, tried to cut corners etc. which is why most have some sort of problem either out of the box or later down the road. This isn't to bash on Corsair as they did/do what they can to build a good enough product at a price point the market can accept-basically cheap enough and fast enough. You could build it right, still do so quickly but it would likely cost a good deal more. Or you can build it right at a reasonable price point but not very quickly which is my understanding of the F-22 production situation. This approach also mirrors the Exocet Moth build approach (limited to 20 a year as well to avoid a cut in quality or hike in price).
  10. samc99us

    Nacra F18 infusion MK3

    You can almost never have enough rigs... I like the teal Edge on top, but I'm a tad partial to that color (teal boats are fast in my experience). @ eastern motors, that is a bit of a loaded question as there are many variables. The short answer is probably not more than $5-$6k ready to roll with trailer and good sails. I say this as I have seen some Capricorns for sale in that price range recently and they are a much more competitive boat than almost all Hobie Tigers. Used Infusion Mk. 1's can be had in the $8-$9k range with good sails, Mk. 2's are coming down into the $12-$14k range for older models and C2's can be found in the $10k range. All of these are more competitive boats than the Tiger if you can find/afford one. Also don't underestimate the value of good/new sails, you're looking at a $4k+ check for a complete set from all the lofts these days.
  11. That is a great question Bruno, IDK what the Cat 2 rules specify. I know they used to be advised but not required for most major races. The 2015 Transatlantic Race was the first race I participated in that required the AIS locator beacons (I carried a PLB as well); I think it was one of the major findings to come out of the Speedboat/Rambler Fastnet capsize. It took a while to make its way into the rules and for the equipment to become readily available.
  12. These products meet the requirements for the Newport-Bermuda race:
  13. samc99us

    Nacra F18 infusion MK3

    The Infusion Mk. 2 has won more F18 titles than any other platform in the history of the class. One took 3rd and 6th at the F18 Worlds in 2017, so its hard to say that the hull shape is bad or the platform is slow/outdated. I still find it one of the best all around shapes and more easily driven in breeze than most. For off the beach work, it has the best rudder system. If looking at new boats it is very hard to ignore the performance of the eXploder Scorpion which has now won every major event there is to win, Worlds 2017, Catacup 2017, Europeans 2018 and the Archipelago Raid 2018. Having sailed/owned both I think the Scorpion has an edge in lighter conditions and in big breeze compared with the Infusion, in the mid range it is similar to the other platforms, maybe a tad faster than some but its mostly the crew at that point. The Edge performs well in a variety of conditions and Brett build a high quality boat/package. I'm quite sure Brett and Max will do well at the Worlds this fall. The Cirrus R2 has also had some top 5 performances. I think the C2 remains a fast boat for lighter teams and professional drivers that can sail blindfolded in the big stuff and avoid pitchpoles. If you look at the underwater shape of the C2 and Scorpion they are not drastically different, but the Scorpion has noticeably more volume and freeboard that make pushing in the bigger conditions easier. Main point here is to get on a boat and come sailing!!!!+
  14. What was the solution so others know for the future?
  15. Hey Dazz, Not something I have thought about. It would also make the wheels completely disassemble pretty quickly which could be handy in a few situations. -Sam