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There is a tool for doing the peeling. Used in lead paint removal operations. Tool is around $250. I figured I'd spend a couple days doing it when considering it. Needs a vacuum hooked up. 4k is a laborer for a month…
a couple years of polymer engineering drifting into my vocab.Glad the original foundary was found. Wonderful find. Perhaps the shop will make a few extra pieces on the setup and hold them for future sale.do not… and i mean seriously do not do this. The cost to produce a mold and produce a replacement is insane compared to the cost of making the part individually. Perhaps your friend will do it for free, but your burning up a very very big favor.Perhaps your friend is willing to do it for you, but a mold could be 10k+.
Remember, the invest cast has to be cut out of big damn block steel, so your spending all your time machining a big ass block of steel when you could be machining your parts. You normally have to make a high number of parts before recovering your costs, even with prototype molds.I would suggest you model a new strut (how ever you like it) and have it cut from stainless.
I have access to a 3 axis CNC and the proper modelng software.TomBest thing to do would be to fill the case with oil. It will facilitate heat transfer out of the case into the environment and keep temps down.Speaking. Of motor sailing… Here's an amateur question.
How does one account for fuel consumption and speed when motor sailing with, say, 10knts of wind. What would the boat normally achieve under sail, what kind of fuel consumption could one expect to reach hull speed.Alternatively, if one had 20 knots of wind, could one exceed hull speed for a low fuel burn? Say an extra 2knots makes a big difference in a long passage..TomI would think it would depend on what type of socket screw you use… Grade 8 has one hell of a shear strength.Here's a little quick engineering math.Quick calculation… assume 55 hp at 2000 RPM, resulting torque is 195 ft*lb. Convert to In*lb 2340 in*lbTotal area of the bolt under load, say its a 1/4″ bolt is pi*.25^2 = .196 in^2We assume that the load is transferred as a shear force rather than a torque (it is resisting a torque, but it is applying point loads to resist the torque)So, now the actual value of the point load. Say the bolts are 2″ from the center line of the torque. Torque = Force * distance2340/2 = 1170 Lbs.So now we know what the load is required to hold the torque load with a single bolt. Divide by the number of bolts to get the actual force, but for sake of the discussion, lets just use 1.Stress, in this case shear stress, = Force / Area = 1170/.196 = 5696 PSI (pounds per square inch)minimum yield strength of a grade 8 bolt is 130,000 psi…The next lesson here would be the calculation of the fatigue strength of the bolt in said condition. If anyone cares for it, I can run that down too…. but generally it starts by dividing your ultimate tensile strength in half (in this case ultimate is 150,000 PSI) and then applying a bunch of factors to determine the yield strength for infinite durability. You divide that number by the stress applied and that is your safety factor.. Just a quick guess is that you probably have a safety factor somewhere around 2 or 3 with a single bolt holding the load.My real concern in this situation would be corrosion, which could drastically reduce the strength of the bolts over time. If you have the same material on both sides of the bolt, i would keep them well greased to avoid rust.😉 I’ve actually done full gelcoat recoating. Waterline up on a 23′ sloop… nasty nasty work. Lots of MEK involved. If im going to do it, I’ll have to take her on one long sea trial… down to Toledo where I can put her in a yard that won’t cost me 10k a year to dock and store.
Always appreciate the words of caution, and for what its worth, I head them.
I am, quiet honestly, looking for something that needs some work. I’m an engineer, and to be honest, I relish hours of mindless drone work.** Just got off the phone with the broker. **
Mind you, the boat was fully updated in 2009 and is now listed for 35k… so, this should be expected.
http://www.yachtworld.com/boats/1983/Pearson-422-Cutter-2928937/Charlevoix/MI/United-States#.VrJWa7IrK70Surveyors report
“the hull was sounded, mallet tap test, and is not in suitable condition on the port side. Dull Resonance and voids sounded, approximately a 6’x4′ area. On the port side, the moisture recordings were elevated to wet for approximately 18′ long x approximately 5′ and up to the bootstripe. Fairing compound non existing at the strut.In the engine bilge and bilges, voids sounded on the whetted surface to port and elevated moisture recordings”
Broker noted a through hull right in the middle of all of this mess that looks to be poorly repaired. I’m thinking that in combo with a barrier coat over the course of a decade could create this.
Wondering what the chances are of the voids that were sounded out not being de-laminations (see thermography idea below)
Would freeze thaw in Upper MI and MD promote de-lamination?I know that I could do flash thermography imaging on the port side… basically involves hitting the surface with a really strong halogen lamp then watching it cool with an infrared camera. Heat will dissipate slowly in front of a void. She’s thoroughly under priced, there is a possibility I could come out ok if i knew just how bad she was banged up.
Yeah… my bullshit filter is up on the cored decks. I’ve heard of it though. They are out there. Unicorns.
Maybe I’ve found a deal.
