gearboxes and potential

Discussion in 'Boat Design' started by bobber, Apr 23, 2004.

  1. bobber
    Joined: Apr 2004
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    bobber Junior Member

    Ok, need some advice.
    I have been designing a boat that runs on a normal 4cylinder, 2 litre engine, however, the prop is connected to a 5 speed gearbox.

    I know they did experiment with automatic gearboxes for racing boats a while ago, and found they wouldnt work, and have since scrapped the whole idea, and manual gearboxes have long had problems with boat applications, due to the lack of momentom whilst changing gear, causing the prop to slam into the next gear and just bend or damage the drive system.

    I have designed a way around this problem. My designs call for a gearbox that can be changed using thumb controls on the steering wheel, and incorporates a system that keeps the prop turning during gear changes, at the same speed, as well as a system that allows a 4cylinder car engine to be used without marinisation, yet still using raw water cooling.

    Unlike a car though, this system will not use a clutch, and so gear changes should happen within 1 second. Making it not only easier for the driver, but also faster.

    however. I dont want to go out and spend the awful anmount of money to frabricate these systems, without first getting some outside opinions.

    In theory. the current drive systems are single gears, and are limited by the revs of the engine. With the gearbox, the revs of the engine can be controlled and the revs of the prop can be increased much more, in theory allowing you to accelerate much faster, and then once on the plane, change the gear ratio so your engine is revving at much lower revs, without sacrificing any prop speed thus boat speed.

    It would only be useful really on planing craft, and for racing or high speed activities, but the intention is to give a boat more car like performance, with a hopeful fuel saving in the process, as you can use a smaller engine, that wont have to work as hard.

    Any ideas on this? Really any problems people can see, which i might have missed, or need to be addressed. Would this be something people would really find useful in a boat?
    negative and positive opinions would be appreciated.
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Manual transmissions have been used with limited success using hydraulic ram shifting. Automatics are better suited for this and have had more success, though the best setup, if you want to match engine RPM to conditions or prop RPM to conditions, is with a hydraulic drive and variable pitch prop.

    The engine drives a pump which drives the oil which turns the shaft via a few different engineering ideas, but most a turbine. The prop pitch is controlled with the same pump setup (there are electric and hand cranked versions too). This allows the engine to be mounted anywhere you want on real soft pads (no vibes man) The hydraulics produce a variable reduction gear in a way where the engine RPM is independent of wheel speed. In a heavy go you can speed up the engine RPM and slow down the prop or in light stuff you can dial down the engine RPM with a fast spinning shaft. Tossing adjustable pitch in opens up even more options.

    This is quite popular over seas, but hasn't caught on over here for some reason. Americans seem to enjoy the séance necessary for selecting a prop and engine combo that will work for them.

    I'm not sure how you intend to give a boat a car like feel, what's the point? Personally I like boat feel as it is and wouldn't want to think I'm in a car. You could buy an Anphib-a-car or something if you want that kind of thing, but none engineered so far has had much success making a car into a boat or a boat into a car. Both require so many compromises to make a successful effort in each working environment that compounding the envelope with the additional complications of being a "car" or "boat" would defeat the point of either. A car will be a poor boat at best if it is to be a car and a boat would make a poor car if burdened with boat stuff. Cats make poor dogs, but I did have one that tried to bark.
     
  3. gonzo
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    gonzo Senior Member

    An engine without marinization is dangerous and illegal. It should have shielded electrics a marine fuel system and flame arrestor as a minimum. Also, car engines are built for different service. Among others, the torque curve, advance curve, fuel delivery, oil pump, head gaskets, pistons, are different.
     
  4. bobber
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    bobber Junior Member

    When i said without being marinised i did mean without needing to pump salt water through the engine. I should have been a little more specific, obviously there are some things that do need to be changed. i didnt know it was illegal though. Must be a US thing, as ive never heard of it being illegal in the UK, ive seen many boats running car engines without problems, other than the cooling problems. But i hadnt really thought about al that you said, and maybe it would be easier just to use a small marine V6 or something.

    Do you know of any examples of where automatics have worked? I know they did experiement with them, maily in the racing field, but last i heard they wouldnt work, they would get to top gear then stop there and wouldnt change again, MAde them fast in straight lines, but slowed them down in turns etc, but its been a while since i have heard of anyone trying it, so would be interested to see it in action.

    I know about hydrolic drives, but ive never really seen them used in smaller power boats, more common in the bigger work boats etc, or in the UK at least, im new to the US so still finding stuff out over here. Hydrolic drives have been used in the TUG industry to great effect, as well as smaller pilot boats, but often not put in pleasure boats due to cost.
    I have noticed a lot of differences between Europe and the US when it comes to boats. US seems a little more happy with what they know works, and dont seem to advance as fast as Europe in boat design. RIBs, which is my field, seem to be the black sheep in the US, most dont know what they are, or seem to stay away from them, only a select few making them in the US, biggest one being Avon, which is a UK company anyway. In Europe, everyone has them, liek the biggest thing in boats to come out of the 60s.

    Not intending to make a boat like a car or visa versa, idea was to get the economy and performance of a car. would use a semi automatic gearbox, eliminating the clutch and everything that goes with it. wouldnt even really need 5 gears, 3 would surfice.
    Main area of use would be for racing, i can see the idea of having to change gears a turn off for the average boat user, and not important, but in the racing field i could see the potential of faster speeds with less fuel load being beneficial. Must admit, i prefer to just have a throttle to worry about, without the added things with gears, but for some its all about speed, and thats where i feel it would work.
    thanks for the imput though, valid points, some i hadnt thought about, got so caught up with sorting out the gear change problems, i forgot the basics.

    On a side note, since mentioned US Vs Europe. Is it required by law in the states to have a power boat license to use a boat on public waters?
    In the UK it is not required, and ive always said thats stupid, as to many people can buy big fast boats wih no training and go out on the water. but i heard, and was told during my training that in the US it is a legal requirement. but as far as i know, here in TN, it isnt. Is it just in some states? anyone know?

    I have RYA level 1 and RYA level 2 powerboat certificate, as well as RYA Safety boat/resuce craft operator license, and RYA instructor certificate, and since RYA is an internationally recognised standard, i thought i might start up a training business to train people on the use of powerboats, but didnt know if it was a required thing by law or not. Just a little business venture i had thought about to keep me occupied until i can afford to set up my own business in the states doing the RIBs etc.
     
  5. gonzo
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    gonzo Senior Member

    The US desn't require an operator license either. All European countries have regulations for fuel and electrical systems. Check ISO for more details.
     
  6. bobber
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    bobber Junior Member

    well thats kinda stupid. should be mandatory that a license is required to operate a boat. people seem to have this idea in their head that boats are safer than cars, when they arnt! still in control of a fast moving lump of GRP or whatever, still kill someone or yourself quite easily, especially at sea, to many people go out to sea in these big expensive powerboats, thinking cause its expensive, its safe and have no idea about the sea, or how to use a boat in it, then when they get into trouble, call the lifeboats, or coastguard, get rescued, and do it again, not stopping to think maybe they screwed up in the first place! ugh. and jet skis, im not even going to get started....

    Sorry, hit a nerve there. where was i
    Oh yeah, i couldnt find anything on it, pages wouldnt load for some reason, but ill take your word for it, you obviously know what your talking about there. I know there are regulations for electrical and fuel systems on boats, but didnt know using car engines was actually illegal in itself. but then its not something i have done personally, just helped other people carry out such projects as favours. I always work to Lloyds guidlines, and never needed to look into marinisation before, but ill have to check into that further, more for curiosity now than anything, as i think ill scrap the whole car engine idea, actually going to put the whole project on hold for now.

    One other idea that someone else suggested to me, who isnt actually into boats, but knows some stuff about cars, was use one of the old style automatic gearboxes, the belt driven ones on a cone. Where the belt is put over a cone, and as the speed increases, this belt is driven up the cone, which gets bigger in diameter, changing the ratio as it goes. Smooth, no gear changes required, all works from centrifugal force. Sounded quite nifty, but i dont know if and where you cuold get those gearboxes now, and there must be a reason why they dont use them anymore, so i dunno. but thanks for all the info.
     
    Last edited: Apr 24, 2004
  7. gonzo
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    gonzo Senior Member

    There is a huge difference in power requirements between a car and a boat. Particularly planing hulls. A car needs a lot of torque to reach operating speed, and then a small amount of power to keep the speed. Boats need increasing torque with higher speeds, and need continuos torque. To acheive this, camshaft, fuel delivery and advance curve are different. Also, they run at twice the RPMs a car engine does. Piston temperatures are much higher, that is why the termostats open about 40-50 degrees colder. The electrical requirements are to prevent explosions. Marine engines are enclosed not open like a car's. Fuel hose have to be double wall to prevent fumes. Fuel pumps are different too. I posted all this before, it is pretty lengthy.
     
  8. PAR
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    PAR Yacht Designer/Builder

    I'm not sure what kind of engineer you think you are Bobber, but frankly the marine conversion from auto application isn't as practical as you'd think. To double what Gonzo has been polite enough not to beat you with is the fact the marine engine lives and operates in such a different environment and under such greater strain than an auto application engine, even with flame arresters on all the needed parts will have a very short life in a boat of any kind planning or displacement.

    An auto engine provides 20% of it's output 90% of it's operating life. A marine engine produces 90% output 90% of the time it's in operation. The engineering involved in designing an engine or propulsion system to handle the service necessary for marine applications is much more demanding then a car. Basically this means you take all of the moving parts in a car block and toss them in a pile and replace them with forged, continuous duty parts. New crank, piston, connecting rods, cam, timing arrangement, valve train (no stamped steel, but forged parts) Fuel delivery, cooling, electrical, vapor return and containment, and a host of other issues need addressing and must meet USCG and other regulations, before it can be in service. Even the lowly carburetor must have it's vent's sealed, it's shafts sealed and even the incoming air (if open to the engine compartment or bilge) must be shielded. An auto carburetor could be bolted on, but please let me know first so I can buy a bunch of life insurance on your soon to blow up butt.

    Clearly you are very young and new to this or very old and haven't kept up (or not what you suggest you are) Hydrostatic transmissions have been around for several decades, are in service now and aren't that expensive. Hydraulic drives and variable pitch props are in service now, have been for years and aren't any more expensive then a new trans and shaft installation.

    Gear boxes on boats don't work well because of the simple physics of hydrodynamics. It can be forced into gear at idle or just off idle as it is in outboards (though most shut down the ignition system for a moment as this occurs) or shaft setups, but once you have a full load on the engine, shaft, prop and other related gear the shock WILL break things. Racers have tried this for years and have been willing to replace parts at an alarming rate, but that's the nature of the business. The average owner, interested in going fast doesn't need the extra tenth of a second he'll get with a gear box, quite content doing well over 150 MPH on inland lakes, rivers and in open water with an I/O, outboard or shaft arrangement without the complication of gears, breaking parts and breaking the laws of hydrodynamics.

    If you've come up with a way to shift gears, maintain shaft speed, release and then reengage the load without breaking things, all within the blink of an eye (a very long time in the gear shifting scale of time) I'm quite sure many manufactures will want to talk to you about your ideas and services. Bone yard engineering is great, but no manufacture will put a name or warranty on it without the math to back it up. Keep thinking out of the box, but do the math.
     
  9. bobber
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    bobber Junior Member

    PAR. i appreciate your comments, but i feel i must say this, as this is something you seem to keep doing, not just with me, but with other people around here.

    You are obviously very experienced and knowledgeable in the marine engineering field, i dont know what you do for a living, but obviously been doing it for a while. I am young, 25 actually. Do not have nearly as much experience as a lot of people on this board, and never claim to have. You obviously do. However, instead of being constructive and sharing your knowledge to help others, you seem to just slate them, treating everyone as if they are some kids in school.

    I have never claimed to be anything. I can tell you what i am, if it will help you. I studied leisure boat design at Glamorgan University in Wales, UK. One of the very few universities in Europe that offer the course specific to leisure boats.
    I worked for Princess Yachts for a short period of time, before going to university, and after graduating, i started playing in the boat field. I dont have my own business, yet. I started one in the UK, building custom RIBs, but got married before i coudl establish it and moved to the US. I have built my own RIBs from my own design. They are not brilliant granted. i am still new to it, and learning as i go, thats what life is all about. I have customised boats, designed numerous boats, and helped other people with all sorts of boats from remote control racing boats, to single inboard powered catamarans.

    Im a learner. I like to learn. If i dont understand something, i ask. Sometimes i try and help others. Sometimes i may be wrong. on boards like this, thats where other people step in and correct. I then learn from that.

    In this case, i had already said i wasnt going to do this project. I asked about it, Gonzo informed me of the problems, OK, thats that. i now know why it wont work, and have learnt from it, so i dont understand why you feel you need to step in and slate me. The comments you make a valid, but the way you make them puts people off from learning any more. You make them out to be stupid, and obviously you have the knowledge to help people.
    I dont know if comming on this board is like a chance to relieve some built up stress from the day, or if you really are the way yuo make yourself out to be, but just think you could help so many people, if you were just nicer about it. like i said, its not just me, a number of other posts on here, from people asking genuine questions, who may not be as clued up as you on it all, and you put them down, instead of politely informing them off the situation and maybe suggesting alternatives? or ways around the problems that you may find with their question.

    Anyway, just thought i had to say that. Listen or dont, your call, said my part, ill leave it at that.
     
  10. tom kane
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    tom kane Senior Member

    Do not let anyone steal your dreams bobber.But as you are doing...you must check them out.Here in New Zealand we do not as yet have any one telling
    us how to build private boats..but it is coming.Many of us are sorting out many ideas about boats.Particularly about safety in fuel systems,it is very difficult to make the experts listen as there in no system for this.
    Many experts do not want to see change from their ways or even do research about ideas they are not familiar with.We should all still keep trying.
    There are many Good engineering practices which are not put to use because
    no one bothers to try them out.Tom Kane. :rolleyes:
     
    Last edited: Apr 25, 2004
  11. woodboat
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    woodboat Senior Member

    Two small things: In the USA many things are left to the local government IE the states. In Maryland you must pass a safe boating course before you may operate a boat. Old timers are Grandfathered in :) Also I took a stock V8 Chevy engine out of a Nova with +200,000 miles, slap on some rings, bearings and Marine headgaskets. Put in in a 26 FT Trojan and ran it for three seasons without incident. It was then transplanted into a commercial crabbing boat for two more seasons, again without incident where it sits today. I too would recommend a beefier engine But.. in a pinch or for testing it can be done. On the transmission Idea there are Constant Variable Transmissions in Subarus right now. As you described with two cones that move in opposite directions. This would eliminate the crunch and breakage of traditional transmissions. What I don't know is if you could build such a transmission that would be beefy enough to endure the high torque demands of a Boat.
    http://www.swri.edu/3pubs/brochure/d03/cvt/cvt.htm
     
  12. bobber
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    bobber Junior Member

    thanks tom.. I dont let it get to me, just sometimes feel ihave to stick up for myself, i dont like being made out as stupid, i do that well enough on my own sometimes. Think a lot of the time, the hardcore marine engineers and such are afraid of the younger people comming in. Cant think why though. Im sure when they first started they had to learn sometime, werent born with the knowledge they have now. I dont know what they think we do at university, but i know i spent a good month learning about hydrolic drives and such, but can only speak from experience in the UK. what people do in the US is new to me, maybe there are thousands of 20foot bass boats tearing around lakes running hydrolic drive systems, i know there are a few companies in the UK that use them on smaller pleasure boats, but not enough to call them significant... Thats where a lot of the problems arise, i havnt had any experience outside the UK. But my ambitions are set. ill get there, may take a while, but i dont do it for the money or anything, i do it cause ive been aroud boats since i was 4 years old, and love working on, around or with them.

    woodboat. Nova V8 maybe a bit overkill for what i had in mind, but nice to hear from someone who has made it work on here. I wanted to stick with GM engines, hence the Calibra, but i dont think i will bother for a while. Got hundred and 1 other projects either on the go or lined up, this one is obviously going to be a long haul, and require some more thinking, so ill put it on hold and maybe come back to it later. (probably read in a few months how some company is making billions off the idea, but oh well).

    Im curious about the transmission though. I really didnt realise they still used them. I know DAF did many years ago, and think Volvo did too, but i didnt know they still were. Im not really clued up on cars, i learn as i go there and just learn what i need to fix when it breaks, otherwise i dont really pay much attention. But subaru use them hey? I have a subaru Impreza WRX, but its manual, so obviously not the same, but do the new subarus use that transmission then?
    I would imagine they wouldnt stand up to the pounding they would get, but was interested because of the lack of changing gear so to speak, smoother and much less shock loads etc yeah. i dont know about that sort of engineering. i wouldnt know where to start with building a transmission, things scare me to many cogs and springs to keep track of, i would just use an existing one and modify it if required, if i did it.
    but thanks for the info. curious now, going to have to look around and see examples of them. I remember driving my nans old DAF years ago, before i could drive legally, and remember a little bit about it, but also remember dad swearing and cursing because the belt slipped off, or something like that.....
     
  13. woodboat
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    woodboat Senior Member

  14. Joe C

    Joe C Guest

    Bobber

    Thought i would add that here in ontario we are soon to be required to have a licence to use a boat i think the main aim is at PWC and the lack of respect to others stuff. as for non marine engines in boats i have see a fair amount that work great and have lasted a long time. one being a tug of about 25' or so, powerd by a chev 350(with marine carb and exhaust). another being a dive boat of 35' (roughly) powerd by a ford 302(out of a 85 crown victoria with 260,000Km). the dive boat wil get up on plane fairly quick im told.
    anyways just a little input
    Joe
    ah on a side note im also a "Pee Wee" being 21, altough i have been on tugs and various other boat for the last ~15 years.
     

  15. bobber
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    bobber Junior Member

    found out the other day that here in TN you are required to have taken a test, if you are over 12 years old and born after a certain date, which i cant remember now, but was in the 80s. the test is kind of like the driving test. its more about the law than actually how to drive a boat, so pretty useless. all the other certificates and tests are optional and not required, so i doubt many people have bothered with them.

    PWC are the mother of all evil on the water. Unfortunately, not all PWC users are bad, but those who are speak the loudest and set the reputation for everyone else as being inconsiderate and darn right dangerous.

    i remember a group who used to try and mess with me, comming up really close to try and spray me, and fumping my wake etc, cutting in front of me. They didnt realise i was in a RIB and frequantly went out many miles offshore in anything up to force 7/8 gales sometimes, so getting a little wet was part of the game to me. and when then cut me up, i would just keep on going. if they hit me, it was going to hurt them more than me, as they will just bounce off the tubes and throw themselves off, wouldnt bother me. they soon left me alone and terrorised someone else! but they are a problem, especially in the UK around beaches. they ignore no boat areas and mess where swimmers are, because the are usually quite fast, police boats cant catch them, but now the police in a lot of areas have a fleet of jetskis themselves, to even the playing field a little. the police in wales where i was took delivery of a delta RIB, which blows most pwc out the water when required, and has helped a lot on the waters around milford haven.

    as far as the car engines go. it does seem that they have been used to great effect by a lot of people. i think the problem was they are not the "proper" way of doing it, kind of like a 1934 ford wasnt intended to have 502hp V8 bolted into it. but hasnt stopped anyone. i know a friend at uni was doing a single inboard 21foot catamaran and he had a 2.8 V6 ford engine to go in it from a car. a company sold marinisation kits for the engine locally, and just bolt on some water cooled manifolds, carb and some stainless steel fuel lines and it was away. no electrics on engines like that so no problems there. as far as i know it all worked, i moved away before he finished it and lost contact, so i dont know if he ever did get it in the water. was a good design though, i know we spent many hours up all night designing how to put a single inboard in it, even had a couple of top naval archs.. throwing in ideas on it to make it work.
     
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