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Don't rotary engines put out very little torque in general? In a marine environment I don't think that would be good.
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Aug 10, 2016 18:49
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Atkins Marine Rotary Engine, and the very first link prominently greeting you on their site is for putting a supercharged rotary in a boat. That is quite likely the best worst idea for a marine engine.
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Aug 10, 2016 18:51
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evilcat posted:Atkins Marine Rotary Engine, and the very first link prominently greeting you on their site is for putting a supercharged rotary in a boat. "We only guarantee the first start"
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Aug 10, 2016 19:02
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Why is a rotary boat motor a bad idea aside from a lack of torque? It seems like it would be happy running at high rpms for an extended period of time and the basic motor itself if based on the 12a would be fairly reliable given you don't have to have the whole nest of vacuum lines running everywhere for 14 million little different things. The biggest issue it seems would be keeping everything cool down in the bottom of a boat. Maybe I'm just dumb though.
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Aug 10, 2016 19:38
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Elmnt80 posted:Why is a rotary boat motor a bad idea aside from a lack of torque? It seems like it would be happy running at high rpms for an extended period of time and the basic motor itself if based on the 12a would be fairly reliable given you don't have to have the whole nest of vacuum lines running everywhere for 14 million little different things. The biggest issue it seems would be keeping everything cool down in the bottom of a boat. Maybe I'm just dumb though. Because even non-turbo rotaries are not known for their longevity, and longevity over very long running times is kind of essential for a boat.
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Aug 10, 2016 20:31
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I feel like, if you're putting a rotary in a boat, you're doing it more for fun and top speeds, accepting that you're going to have to rebuild it every now and then (probably after paying a buddy a case of beer to tow you back to the marina).
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Aug 10, 2016 20:41
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Safety Dance posted:I feel like, if you're putting a rotary in a boat, you're doing it more for fun and top speeds and less for longevity. Except the speeds a rotary turns at, in THAT style boat, is more just a recipe for cavitation damage to the prop.
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Aug 10, 2016 20:42
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CommieGIR posted:Except the speeds a rotary turns at, in THAT style boat, is more just a recipe for cavitation damage to the prop. I feel like, if you're putting a rotary in a boat, you probably understand boats about as well as I do and are willing to accept some expensive lessons in practical fluid dynamics.
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Aug 10, 2016 20:43
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CommieGIR posted:Except the speeds a rotary turns at, in THAT style boat, is more just a recipe for cavitation damage to the prop. I would expect that there's a transmission in between the motor and the shaft... which could drop the revs to something resembling sanity. I know the big boats I've worked on and run usually have ~2:1 reduction. We're certainly not spinning the 42" wheel at 1800RPM.
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Aug 10, 2016 20:44
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sharkytm posted:I would expect that there's a transmission in between the motor and the shaft... which could drop the revs to something resembling sanity. I know the big boats I've worked on and run usually have ~2:1 reduction. We're certainly not spinning the 42" wheel at 1800RPM. Correct, ski boats have reduction gears, commonly referred to as velvet drives.
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Aug 10, 2016 21:38
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Direct drive fixed pitch forever. nthing the amazement at a rotary marine engine, too. Maybe in a tiny speedboat you gently caress around with on a lake or something, I guess.
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Aug 11, 2016 02:09
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It would certainly sound interesting!
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Aug 11, 2016 02:20
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Cooling would be easy, you have lots of coolant in a lake/ocean. Boat people already use premix, so don't need to worry about oil injecting. Just need a different reduction gear for the motor. Sounds like a good idea to me. Outboards rev at 6k rpm, so thats no different. Id use a rotary in a boat. But Im probably dumb too.
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Aug 11, 2016 02:24
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That's not a boat you would really take far offshore, and it has an outboard, so not a huge deal if your rotary fails (unless it grenades and sinks the boat). It's not like someone would try to cross the Pacific on a boat like this.
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Aug 11, 2016 02:32
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If there's someone who wants to buy a sixty year old dump truck on the other side of the country, swap a new motor in it and drive it home, there's someone who wants to cross the Pacific in a rotary-engined speedboat.
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Aug 11, 2016 03:00
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boxen posted:If there's someone who wants to buy a sixty year old dump truck on the other side of the country, swap a new motor in it and drive it home, there's someone who wants to cross the Pacific in a rotary-engined speedboat. Fair point.
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Aug 11, 2016 05:01
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evilcat posted:Atkins Marine Rotary Engine, and the very first link prominently greeting you on their site is for putting a supercharged rotary in a boat. Oh hell no. Run away from Atkins. Their parts and engines are questionable at best. God forbid you put one in an aircraft.
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Aug 11, 2016 08:03
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the spyder posted:Oh hell no. Run away from Atkins. Their parts and engines are questionable at best. God forbid you put one in an aircraft. Not sure if its atkins, but there is a company that sells a version of the wankel engine for aircraft.  So, if one were to take the atkins portion of the equation out, do you think a marine rotary would have any merrit spyder? Because I'm having some disturbing thoughts about a turboed 20b (or two) in a cigarette boat. Can you make a wankel rotary spin in reverse? Edit: Mainly, even if the engines don't kick out that much torque, they seem like they'd be fine in a lightweight speed boat. From what I understand of rotarys, they like higher revs, but could they take sustained higher revs, like for hours at a time. And would standard cooling from seawater be enough, or would it need some form of supplemental cooling? Elmnt80 fucked around with this message at 08:34 on Aug 11, 2016 |
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Aug 11, 2016 08:30
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Elmnt80 posted:So, if one were to take the atkins portion of the equation out, do you think a marine rotary would have any merrit spyder? 
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Aug 11, 2016 08:48
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Collateral Damage posted:Does a rotary have any merit at all apart from an awesome sound and being able to dickwave your 10k rpm redline around? You get to say wankel alot while talking about it?
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Aug 11, 2016 08:52
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blindjoe posted:Boat people already use premix, so don't need to worry about oil injecting. Most outboards have moved to 4 stroke now, but most 2 strokes in the last 25 years or so do oil injection.
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Aug 11, 2016 13:21
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https://youtu.be/ZdeTj7nyN-s
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Aug 11, 2016 14:50
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Elmnt80 posted:And would standard cooling from seawater be enough, or would it need some form of supplemental cooling? How would you get supplemental cooling that could possibly cool better than the ability to suck in as much cool water as you possibly want that will never get any hotter from your engine running? Boats simply should never have a 'heat' issue, due to the unlimited availability of cooling water. It's like having the ultimate radiator that always delivers 70 degree (or whatever the water temperature is) water to the engine no matter what the conditions are. The only reasons I can think of for overheating in a boat would be a pump failure or extremely poor water jacket / cooling design.
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Aug 11, 2016 16:17
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The Locator posted:How would you get supplemental cooling that could possibly cool better than the ability to suck in as much cool water as you possibly want that will never get any hotter from your engine running? Or bouncing your boat of the bottom cracking the keel cooler. Hard to keep the motor cool if the part that is supposed to hold sea water can no longer hold water. Luckily that incident only put one of the 2 generators out of service and both mains were unaffected. I know a good number of salt water boats pump fresh water through their engines and then use sea water to cool the engine water.
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Aug 11, 2016 17:52
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Negromancer posted:Or bouncing your boat of the bottom cracking the keel cooler. Hard to keep the motor cool if the part that is supposed to hold sea water can no longer hold water. Luckily that incident only put one of the 2 generators out of service and both mains were unaffected. I know a good number of salt water boats pump fresh water through their engines and then use sea water to cool the engine water. Still a hugely better cooling system than air to water radiator. But yea, breaking your cooling parts is always a good way to have heating (or sinking) issues.
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Aug 11, 2016 17:59
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The Locator posted:The only reasons I can think of for overheating in a boat would be a pump failure or extremely poor water jacket / cooling design. Ahem. These bad-boys have a nuclear meltdown if they leave the arctic ocean as the water at the equator is too warm and overheats the cooling system. It's a bit of a fringe case to your point though
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Aug 11, 2016 23:04
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Captain Postal posted:Ahem. Probably a good idea not to take your nuclear powered ice-breaker out of the environment for which it was specifically designed without any margin for safety then I suppose!
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Aug 11, 2016 23:05
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I say buy the boat and a 12 pack of apex seals. Problem solved.
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Aug 11, 2016 23:55
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Popete posted:I say buy the boat and a 12 pack of apex seals. Problem solved. I was more thinking that rotary's are small enough you could keep at least 1 spare motor on board without cutting into the storage space too much. Realistically, I am more looking at something like a Starcraft like this. gently caress the maintenance on wood boats and fiberglass scares me since the problems are hidden. I would prefer a steel boat, but aluminum makes more sense for that size/class of boat. The biggest downside to that particular boat is that I would prefer an outboard.
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Aug 12, 2016 00:03
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I just need to win the Powerball so I can ignore the fact that wooden boats are even more of a money-pit than other boats, and buy this. http://schoonerdauntless.com/index.html
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Aug 12, 2016 00:29
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Captain Postal posted:Ahem. See also the ridiculous number of ocean going cargo ships that suffer black outs in eastern Canada every winter because their cooling water intakes become clogged with ice.
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Aug 12, 2016 02:45
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The Locator posted:Probably a good idea not to take your nuclear powered ice-breaker out of the environment for which it was specifically designed without any margin for safety then I suppose! Thankfully it can cold shutdown pretty quick. Hell, the reaction is scrammed in 0.6 seconds after inserting control rods.
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Aug 12, 2016 02:59
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FrozenVent posted:See also the ridiculous number of ocean going cargo ships that suffer black outs in eastern Canada every winter because their cooling water intakes become clogged with ice. Legit username post combo here. For content, I remember visiting the yard for a company I worked for where they were laying down 10,000 dwt self propelled barges and thought those were huge, but they aren't even handysize!
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Aug 12, 2016 04:15
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I maintain motorboats for a sailing school, and one of them is leaking mayonnaise from the propeller shaft, my lucky day! The engine is a pile of poo poo johnson, model: j50plsib. I'm having a hard time finding any sort of service manual for that engine. Is it a straight forward seal replacement like most outboards? Usually you unbolt some retaining ring, and just pull the seal out, slide a new one in.... or in typical 2000's OMC fashion is it a huge pain in the rear end. I found a parts explosion for a 2002 and 2000 model, those look the same, so by the property of extrapolation (is that even a thing?) I'm gonna assume the 2001 model is the same... https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=2000&hp=50&model=J50PLSSM&manufacturer=Johnson§ion=Gearcase
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Aug 12, 2016 11:51
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Negromancer posted:I was more thinking that rotary's are small enough you could keep at least 1 spare motor on board without cutting into the storage space too much. Fiberglass is great as long as it is just glass and nicely thick or a modern foam composite that doesn't rot. I'll go halvsies with you on one of these: Turbocharged 6v92 pushes it to around 30 knots in the worst conditions imaginable and returns <2nmpg  https://en.wikipedia.org/wiki/30%27_surf_rescue_boat  http://olympic.craigslist.org/boa/5724071528.html Also interested in something like this that isn't a stripped hull. I think with all the net gear removed and the forward most tanks converted for fuel 15 knots would be economical on a fuel injected Volvo B20.  http://olympic.craigslist.org/boa/5712708641.html Why do I only love broken garbage boats?
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Aug 12, 2016 23:04
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chrisgt posted:by the property of extrapolation (is that even a thing?) I'm gonna assume the 2001 model is the same... That would be interpolation! 
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Aug 12, 2016 23:43
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Boat goons, I know nothing about the major brands and models, can someone give me a few recommendations? My dad is looking to buy a boat this year, I'm guessing between 14-20 feet. Fishing boat, but would also be nice if it was nearly multi-purpose and could be used for family fun / cruising/ touring / swimming as well. Also his tow vehicle has a max tow rating of 5000 lbs, so he is hoping for boat,gear,engine and trailer to be under 4000 lbs. We don't know what brands are good (Legend vs Lund vs Lowe Vs Smokercraft ,etc) and whats a good price. We have looked at Legend's X Series 18 footer and this seems to be what we want, but are open to other suggestions. Thanks in advance
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Aug 14, 2016 17:19
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chrisgt posted:I found a parts explosion for a 2002 and 2000 model, those look the same, so by the property of extrapolation (is that even a thing?) I'm gonna assume the 2001 model is the same... Extrapolation is when you make assumptions about data outside the known range, i.e. if the 2000, 2001 and 2002 models were the same, it stands to reason that the 2003 would be at least similar.
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Aug 14, 2016 18:55
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Less sperging more boat chat.... I interpolated between the sun and the moon, this boat belongs at the bottom of the ocean. The bearing retainer has to be pulled out to replace some stupid o-ring that commonly leaks, not to mention similar levels of grief to do the top shaft seal. Anyway, I've already pulled it all apart, figured how I'm gonna press it back together, etc. Parts should be here this week. If anyone has to fix one of these, sell it. It's a miserably bad engine anyway.
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Aug 14, 2016 19:25
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Looking to get some used jet skis. Found some for sale but they are 2001, and one is a Yamaha and the other a Polaris, and the seller says both have new engines. To my recollection, most jet ski manufacturers have basically stopped making parts for older models and they are hard to find, so I want to know if there could be some truth to the sellers claim of new or even rebuilt engines? My budget is not huge so they'd have to be used, but I'm thinking these are too old even if their claims are true, and they are asking $6500. Any thoughts?
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Aug 14, 2016 22:07
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