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About CaptainAhab

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  • Location
    South Australia
  • Interests
    Finding the White Whale

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  1. CaptainAhab

    Turning it upside down

    The one benefit of flipping it upside down is when you inevitably don't finish the work on it. You don't have to cover it. Unfortunately, you won't be able grow plants inside the cockpit and no one will ever come along and take it off your hands.
  2. CaptainAhab

    J24: Anyone ever DIY pull a deck?

    In less than 1 minute I found a pile of J/24's on the class site for +-$5k. Old boats in decent condition. As good or better than you will get your d_ckless hull. Just the material alone to recore a deck would make me buy another boat. Oh wait. I forget "it needs everything". Just a 4hp outboard would cost $1000. You live in the States. You live in RI the home of the J/24. Bury it in the J/Boat cemetery. Its the size of Arlington. In the fall, when there are no leaves on the trees, you can see the masts from 195. In the spring, you can smell the rotting balsa core miles away. Definitely worth a visit.
  3. CaptainAhab

    stupid trim question CE

    Move the pivot of the rudder forwards. Beach cat style is to rake it under the boat. Fancy boat way is make the transom hung rudder so it leading edge is forward of the gudgeon and pintle. Or you can pull on all those strings
  4. CaptainAhab

    I messed up, paint in mast track

    Liberal lubrication until it wears in. The risk of the sandpaper rig getting jambed or wearing away the anodized layer is not work it. The sand paper will probably sand everything you don't want it to, and get stuck where you need to abrade.
  5. CaptainAhab

    2 x 25A => 50A circuit?

    All shit aside. What is the shittiest consequence of putting two loads on the same line? The breaker will trip while both shitters are being flushed. This would obviously cause both to clog with shit. Cleaning up two loads of shit is worse than one. The wire won't melt. The breaker will trip. You will be cleaning up 2 shitty shitters. Keep in mind that simply having one typical 18 amp shit would allow for a simultaneous 7 amp piss. Considering that you are on a yacht, there is higher chance of someone taking a beer piss. Based on the data that could be as high as 10 amps. It will trip the breaker. So the limiting factor may be beer consumption not amperage of shit. In that case you would be cleaning up one shitty head and a cabin sole of beer piss. Depending on type of beer that could be a challenge. Data indicates that watery lager(Heiny) is similar to regular piss. The greater the hops(IPA) the shittier the smell. Stout is approximately the same as a diesel spill in the bilge. Its a tough decision. The shit will be on you if it all goes shitty.
  6. CaptainAhab

    Retrofit Composite Chainplates

    My composite/structural engineer friend is a big fan of glass. He adamantly believes that huge amounts of carbon fibre are wasted in many applications. Its well known that the tensile strengths of carbon & glass are effectively the same. It is well known that the compressive strength of glass is at least 2.5 times less than carbon. This would be on paper in the lab pulling/pushing unidirectional fibres. Proper design can make the compressive strength nearly irrelevant. If you are making a composite I-beam the fibres on one side are always in tension the other side in compression. The tensile strengths are so much higher than the compressive strengths that the tensile is the limiting factor. Therefore you could use either carbon or glass. The grid in the bottom of the 40' race boat was made of glass, because it is essentially a bunch of I & C-beams bonded together. My father and friend are both engineers who worked at EB designing submarines. Jon was the project manager on the largest composite structure in the world back in the 2000's. Its the bow dome of a Seawolf class submarine. 16" of solid fibreglass. Its got to be transparent to the sonar. I've learned a ton from them over the years. Its always a good idea to run some of these questions by someone who knows the math & physics.
  7. CaptainAhab

    2 x 25A => 50A circuit?

    That is half true. If the wire is the correctly sized for 25 amps or rated higher the load item(head) will cook if its overloaded. That could possibly occur if someone took a larger than design shit. The correct wire would overheat loose its cover, possibly start a fire and otherwise turn to shit. The oversized wire would handle the excess load from the head, except the breaker wouldn't trip until it hit 50 amps. If somebody took a 50 amp shit then the wiring in the boat is the least of your worries.
  8. CaptainAhab

    Retrofit Composite Chainplates

    Its surprising how little bond area need when you get someone to do the calculations. I remember when we were building the 40' race boat. We had the boys from NEB help us do the hull layup. We got to use their impregnator. My friend who designed and built the boat is a composite/structural engineer. He calculated that including safety factor you need 2.5 inches of overlap between each roll of tri-ax when using Proset epoxy. The NEB guys had always done 6 inch laps. They built most of Star's and Stripes as well as a slew of other big name racing boats. Imagine the weight of resin and glass of an extra 3.5 inches every 36" across the hull all the way along a 80' boat. Keep in mind the same rule applies every time you make a lap everywhere on the boat.
  9. CaptainAhab

    Retrofit Composite Chainplates

    The other thing to consider is that it is not a stand alone piece of kit. Its bonded directly to the hull sides. The load is spread across a large amount of an existing strong & stiff surface. Delam shouldn't be a concern because of the bonding surface area. The part is in almost pure tension, therefore carbon is a waste of money. I always liked using s-glass for these kind of structures or reinforcements. Unfortunately its been made obsolete by carbon and the availability and cost makes it a poor choice.
  10. CaptainAhab

    Are Mount Gay Rum Hats Cool?

    They are only cool when they have faded to the equivalent weathered shade of Breton red(Salmon?) worn by the old crusty guys that present the awards at Off Soundings. You need to get one at Block Island race week(June) and tie it to a dock and leave it to weather until Fall Off Soundings(Sept). If you are seen in public, (especially at the Mystic River Mudhead Wednesday night summer series) with a red hat you are a wanker of the highest regard.
  11. CaptainAhab

    Retrofit Composite Chainplates

    It doesn't matter if you fabricate them on a bench and bond them into the hull. In fact you could vacbag and cure them out the boat. Whereas you only get to vacbag in the boat. The reality is you will put a ton of extra material regardless of how you do it. Some people do a combination. Make up your turnbuckle attachment on the bench then bond it to the hull. Then add on layers to distribute the forces further out into the hull and down to the mast step.
  12. CaptainAhab

    Keel Bolt Questions

    You don't have any more thread to allow for a thicker washer. Our steel square washers we use in AU house construction are 16mm bolt - 5mm washer. 25mm bolt - 6mm washer. Most backing plates have traditionally been 6mm(1/4") flat aluminum plate, nowadays its 6mm G-10 fibreglass plate. Round washers love to crush wood fiber. Square ones not so much. That is why the spec them in timber houses. 4mm should be adequate as long as you fill in the crushed area. A little car wax is good mold release. Definitely use something. I've snapped many screws that got a wee bit of epoxy on their threads.
  13. CaptainAhab

    Remove thin gelcoat layer -- over CF

    4" grinder with a basic disc sander kit or one of the newer more expensive style ones like Mitre cuts is the perfect tool for composites. We call them detailers. As others have mentioned a good RO sander like a Bosch or Festool with the rotary cut switch will also do the trick. It sounds like you have very little gelcoat to remove 50mm x 1000mm. Any random orbit sander would work fine. Stop using the the wire brush. It will eventually start tearing up the fibres. Those things are ment for removing paint or rust off of metal.
  14. CaptainAhab

    G-Flex vs. Plexus - ABS plastic boat repair

    It looks like Ace Hardware(US), Devcon, & Loctite all sell a plastic repair epoxy. None of them are epoxy. They are all methacrylate. This is the adhesive in Plexus. I've noticed that some of the brands of concrete tie down epoxy is also falsely labeled. Its also methacrylate. Its good to know, since Plexus is expensive, hard to come by in AU and every once in awhile methacrylate is a better choice than epoxy or g/flex. They are also small tubes like 5 minute epoxy.
  15. CaptainAhab

    Mast vegetation??

    Water is the ideal solvent for most bio stuff. Whatever flavor detergent or surfacant you prefer can help. Choose one that doesn't like to chew thru aluminum(Simple green) or plastics. Moving it around with a sponge usually helps as well. If its outside bleach will have zero long term protection. You don't have an infestation. Just a bunch of biological scum.