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Towing vs Davit.....

Discussion in 'Carver Yacht' started by hopper5, Dec 2, 2012.

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  1. Capt Ralph, Dec 7, 2012
    #41
    Capt Ralph

    Capt Ralph Senior Member

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    We all are here to help. Some of us get carried aweigh. Real ships engineers, pilots, shade tree techs (me) and bunches in-between try to help.
    I don't know if you noticed or not, some of these responses come from around the world.

    Keep us up on where you are and there is always a response to be found here.

    ,rc
  2. hopper5, Dec 8, 2012
    #42
    hopper5

    hopper5 Member

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    Thanks again.........If I end up needing bigger props what am I up against for cost?? I assume a good prop shop through their calculations will know what I need. I would hate to buy new ones and still have "issues".
  3. Capt Ralph, Dec 8, 2012
    #43
    Capt Ralph

    Capt Ralph Senior Member

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    Years ago, My local shop would find a used set of wheels to try first (Many years ago). The world has changes and I could not tell you if anybody trust anyone anymore. You can still just ask.
    Or, a fellow boater may let you borrow a set. The exact set not necessarily needed, just something to-wards the recommended size to see if things do improve.

    Have you discovered the factory size yet? Always a good place to start.
  4. jhall767, Dec 9, 2012
    #44
    jhall767

    jhall767 Senior Member

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    There is a good possibility that you will need to try more than one set of props. The boat just may be overweight/underpowered. That boat would not have been considered to have excess power when new. It has now gained weight through the remodel and through adding a heavy dinghy. The previous owner may have decided it was underpowered to run on plane properly and depropped to the situation you have now.

    Right now the boat will cruise comfortably at 9 knots. The engines will probably never wear out at 9 knots. The question is how much are you willing to spend to cruise at 15 or 16 knots?
  5. Capt Ralph, Dec 10, 2012
    #45
    Capt Ralph

    Capt Ralph Senior Member

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    Just wondering, What comments did your surveyor make during sea trials about rpm / speed?
  6. hopper5, Dec 10, 2012
    #46
    hopper5

    hopper5 Member

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    He seems to think that the speed is typical for a boat that size.......He does diesel work for much larger boats as well and has been in busy for 30+ years.......he is a motor man. I am anxious to try some of the things mentioned here. First off...because it's free !!.....I'll lighten the load to just se if thee is a difference.....
  7. hopper5, Dec 10, 2012
    #47
    hopper5

    hopper5 Member

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    Interesting thought

    Here is one for you guys.......I contacted a prop shop and their suggestion as how to check out if my props were the correct size was to increase the throttle slowly and see if I got to 2800 rpm (max Cat recommended) before full throttle position.......ie: If my props were undersized then the governor on the motors would limit the RPM's at full throttle. So if the RPM's were 2800 before full throttle position it would prove the props were too small. If it took full throttle to get 2800 RPM then they are properly matched.........Thoughts ?? It made sense to me.....but that may not be saying much !!!!
  8. jhall767, Dec 11, 2012
    #48
    jhall767

    jhall767 Senior Member

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    If your engine is rated at 2800 rpm it would be preferred that it turn 2800+ rpm in gear. This would be fully loaded with a clean bottom. If it only turns 2800 rpm or less then you are already using everything the engine has to give.

    What they are really looking for is the difference between full throttle in neutral and full throttle in gear. I don't know the exact specifications for your engine but a typical mechanical governor would droop about 150 rpm. So you would be looking at 2950 in neutral and 2800 in gear. On the other hand if they turn 2825 in neutral and 2800 in gear then they are probably very lightly loaded.

    All rpm readings need to be verified by a digital tachometer. If you don't have a digital tachometers you can buy a handheld one for about $50. Also don't use the engine synchronizer if so equipped.
  9. hopper5, Dec 11, 2012
    #49
    hopper5

    hopper5 Member

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    Interesting.......I'll check with my diesel guy before I run them up in neutral I am a bit reluctant to go full throttle when not in gear. Is it not accurate to say that I could do something similar by running them up slowly in gear and see where I get max rated rpm?? That was the recommendation from the prop shop......always something new !! Thanks again for all of the help....great stuff !!
  10. jhall767, Dec 11, 2012
    #50
    jhall767

    jhall767 Senior Member

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    Please do check with your diesel mechanic. What he should tell you is that the proper test for these engines is full throttle in neutral. If it is not able to do this then the engine needs service. These are not like gas engines that you may be accustomed to. The throttles set your desired rpm. They do not set the amount of fuel the engine gets. The governor meters the fuel so that the engines run at that rpm. More load causes the governor to deliver more fuel.

    Kind of like cruise control on your car. Go up hill and more gas gets applied. Downhill and less gas gets applied. Too steep a hill and the engine can't keep up. Overload and black smoke. Your car might downshift but your boat can't.

    PS. Full throttle in neutral SHOULD have been part of your survey.
  11. hopper5, Dec 11, 2012
    #51
    hopper5

    hopper5 Member

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    Thanks...I will call my diesel guy today. I also plan on running the boat Friday so I will check the "unloaded" RPM's.......As you can tell diesels are new to me. I am used to my good old gas motors in my 34' Tolly......There is a learning curve !!
  12. Capt Ralph, Dec 11, 2012
    #52
    Capt Ralph

    Capt Ralph Senior Member

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    All of these last comments go back to what has been mentioned before. No-load vs Loaded rpm.
    I do like the idea from your prop guy; If indeed the throttle stops (full travel) is at the governors (not control head) it could be a simple test. NOT conclusive but a part of an overall diagnostic routine.
  13. hopper5, Dec 21, 2012
    #53
    hopper5

    hopper5 Member

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    OK.......My diesel guy came over and checked my throttle linkage and Cat parameters. The engines should do 3000rpm unloaded and 2800 loaded. We did both and they were right on. Another notable item......evidently my water gage is not working ....ie: showing full and really near empty....so much to my surprise I wasn't running "fully loaded". My thoughts now are to run the boat as is then add water / weight to the front (where the water tank is) and see if my bow down trim condition is resolved......thoughts ?? Maybe just too much aft weight /CG. As i mentioned my only excuse to my lack of knowledge of this boat is that I have only recently purchased it and obviously very much in the "learning curve" mode. I am planning on a short trip over New Years and will report back with my results.......fingers are crossed !!
  14. Capt Ralph, Dec 21, 2012
    #54
    Capt Ralph

    Capt Ralph Senior Member

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    Cool. Now lets pacify me a bit more. What is the factory prop diameter and what diameter do you have now?
  15. RER, Dec 21, 2012
    #55
    RER

    RER Senior Member

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    There's a similar thread running regarding performance on a different Carver model where NYCAP posted a comment that I think applies here as well... the boat was not designed with performance and sea keeping ability in mind - the main selling appeal is the layout and livability... and it serves that purpose well. Many were sold.

    Older boats tend not to perform as advertised when new. Even with engines and props to spec, those 3116's are not going to make that 47x15 30,000lb boat get up and scoot.

    As mentioned in some earlier posts here, it would probably be best to save yourself the fuel burn, engine wear & tear, and noise ...to give up three knots, back the throttles down to hull speed and enjoy your boat.
  16. hopper5, Dec 21, 2012
    #56
    hopper5

    hopper5 Member

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    To the best of my knowledge they are factory spec props.......I'll have to look at my notes for exact size. I agree with backing off the throttles and live with 9 or 10 knots at 1800rpm, but I want to take a trip to Alaska sometime in the future and even though most of the trip is protected there is a bit where weather could be a big concern.......so I'd like to be able to scoot around 15 kts or better if the need be to get out of harms way.........just a thought ..I have a friend with a similar boat and he makes frequent trips to Catalina from San Diego so the "seaworthiness" must not be too bad.......if you listen to some of these threads you would think the 440 is not much more than a houseboat !! I don't believe it .......What trips have you folks been on with your Carvers......??
  17. RB480, Dec 22, 2012
    #57
    RB480

    RB480 Senior Member

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    The boat should still be performing better. To the above post thinking it won't, go back and read my posts about it. I wasn't quoting when the boats were new, it was real world personal experience.
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