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431Re: [J28Sailors] Re: Props

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  • J. Smith
    May 15, 2011
    • 0 Attachment
      My Variprofile (feathering) has adjustable pitch. I think with my last pitch change, I am around 16x11, which gives 6.2ish around 2500-2700 and 6.8ish around 3400.
      From: hansandsharon@...
      Sender: J28Sailors@yahoogroups.com
      Date: Sun, 15 May 2011 10:12:05 -0400 (EDT)
      To: <J28Sailors@yahoogroups.com>
      ReplyTo: J28Sailors@yahoogroups.com
      Subject: Re: [J28Sailors] Re: Props

       

      HI All,
      My Gori is a 16x 11,
      It gives me 6.1 @ 2500 rev,
                       6.7 @ 3000,
      I do not go over 2500 very often, as it can smoke, the Yanmar people
      tell's me to blow smoke once in a while but not often,
      2500 is a very good cruising speed and the Engine sounds good at that speed,
      and getting 6 or 6.5 with new paint is good for the Engine and boat speed.
      I don't think you can "Plane" under Power, down wind with a Spinnaker and a good Wave,
      then it is possible.
      Good Sailing
      J 28
      "Last Dance"
       
       



      ---- Original Message ----
      From: Roy Briscoe <roysail@...>
      To: j28sailors <j28sailors@yahoogroups.com>
      Sent: Sun, May 15, 2011 8:25 am
      Subject: RE: [J28Sailors] Re: Props

       
      I looked at our prop yesterday and it is a Varifold 15x10, so maybe a 9 pitch isn't all that drastic a reduction. I remembered the 15 but I guess that wasn't the pitch but the size. I think the fastest GPS speed we have seen out in the ocean off of Maine is 6.5, which I believe is the hull speed of the boat but we are not maxed out on the rpm, we are 200-300 short. 
       
      Roy
       

      To: J28Sailors@yahoogroups.com
      From: j28_59@...
      Date: Sun, 15 May 2011 01:57:54 +0000
      Subject: [J28Sailors] Re: Props

       


      I replaced my 16 dia. X 14 pitch Martec with a 16 X 12 ($839) because of the same issues. Gary at Martec was very helpful. My boat now will reach full engine rpm when the bottom is clean. The bow starts rising out of the water and the exaust is under water an inch or two and boat speed is about 7.25 knots. It is much better than it was but I feel like maybe I could have gone one pitch size smaller yet(16X10) because the engine is really working hard as the boat is trying to get on a plane.
      When the boat was out of the water I checked the location of the screw heads on the shaft coupling and found that they lined up with the prop so I just rotate the shaft to align it. If it is right and you turn it 90deg you can hear the blade drop, if your not going too fast. So when you hear it drop turn it 90 and your good.
      Marc
      S/V Thumper
      Seattle WA

      --- In J28Sailors@yahoogroups.com, Roy Briscoe <roysail@...&g t; wrote:
      >
      >
      > Yeah, I would do some research on the prop sites, like Gori, Max prop, Martec, Flexofold. I wouldn't think you would want a 9 pitch, too drastic a change from 15. We do tend to max out around just over 3K and could probably use a slightly lower pitch. I'll take a look today to see what we have. I know it is a Martec folding with gears/teeth and the shape looks like it is "racing" prop as opposed to cruising prop, meaning less surface area, it came with boat. When we sail, we just put the tranmission in reverse and we are done. W/O the geared prop, you need to remove the steps so someone can turn the motor, get a flashlight, maybe get into the cockpit locker, remove the access panel and set the drive shaft, which is hopefully marked with some white or reflective paint, which is a 2 person job.
      >
      > We have to plan when we back up, it takes a bit for the boat to get moving, even from a dead stop. Maybe the cruising version would h andle this better, or a newer version of what we have.
      >
      > Roy
      >
      >
      >
      > To: J28Sailors@yahoogroups.com
      > From: hansandsharon@...
      > Date: Fri, 13 May 2011 20:06:00 -0400
      > Subject: Re: [J28Sailors] Rudders/Rig tune
      >
      >
      >
      >
      >
      >
      >
      >
      > The "Gori folding prop is very good unit, it has teeth, intermesh so both blade folds as one,
      > I have a 16" which I think is a big a 15 or 15 1/5 will be good, but I do get good boat speed and it backs up very good.
      > The new J boats are using the "Flexofold" which is also a good unit, special for Racing
      > Good Sailing,
      > Hans,
      > J 28 "Last Dance"
      >
      >
      >
      >
      >
      >
      > ---- Original Message ----
      > From: john power <sailingmaster@...>
      > To: J28Sailors <J28Sailors@yahoogroups.com>
      > Sent: Fri, May 13, 2011 6:12 pm
      > Subject: Re: [J28Sailors] Rudders/Rig tune
      >
      >
      >
      >
      >
      >
      > Thanks
      >
      >
      > Not sure what you mean by teeth, the prop I am thinking of buying is a 9pitch by michigan wheel co
      > Its advertised on the j30 site.
      >
      >
      > Thanks for the rig tune numbers
      >
      >
      > JP
      >
      >
      > On May 13, 2011, at 7:43 AM, Roy Briscoe wrote:
      >
      >
      >
      >
      >
      > I think the J30 numbers are way too tight, and my J30 buddy thinks the J30 numbers are too tight for the J30. We took 5th in the Natio nals last year in Marblehead and had a bullet in one race, and he has won the Shields Nationals 3 times, so I trust his judgement.
      >
      > We played around with the rig last year and seem to settle in the vicinity of 760 for the lowers and 960 for the uppers for 10-1 4 knots of wind and adjusted from there depending on wind conditions. Though 200 lbs in either direction didn't seem to make a lot of difference. We tie the uppers to the lowers at the turnbuckle with some line and don't use any rings through the turnbuckle to keep it from unscrewing. Makes it easier for adjusting.
      >
      > The idea being to get the mast to do what you want and not too to drive it through the bottom of the boat with high tension.
      >
      > Roy
      >
      >
      >
      > To: J28Sailors@yahoogroups.com
      > F rom: sailingmaster@...
      > Date: Thu, 12 May 2011 18:36:45 -0400
      > Subject: Re: [J28Sailors] Rudders
      >
      >
      >
      >
      > Thats what I figure is wrong with my rudder. The previous ownders paid a ton of money to the boat yard and had to have the job done a second time. I think the bill got so high that they got frustrated and decided to live with it.
      > I didnt realize how poorly it was done until after I bought the boat. I am hoping to drop the rudder next fall and have the shaft trued, but I dread the bill for this!!!!! I also hope that the wet spot in my rudder might be the fairing problem that Hans mentioned....this gave me some hope.
      >
      >
      > is there a stainless shaft inside this rudder or is it just one massive fiberglass construc tion? I am trying to figure out how the water could be getting in to begin with.
      >
      >
      > I really love the boat so far. The old owners did a ton of up grades. This is just one big problem I did not foresee and it makes sailing the boat a lot less enjoyable. There is NO feel to the wheel and it can be tough to keep the boat on here feet when its really shifty in big winds.
      >
      >
      > Other questions I have are rig tuning ideas, the old owners thought the boat was overpowered do to an old deep main. I think the rig tune was more of the issue. The mast butt was al the way and there is a ton of sag in the headstay
      > (the boat yard tuned the boat to last years settings), so i figure the boat had minimal rake and too deep a slot. I have moved the mast step forward but wondering what people do for rig tension and headstay tension/sag.
      > The J30 numbers seem really tight, and given t he age of the boat I dont know about cranking things up that tight. I probably wont race the boat much this year, but have alwasy sailed fast one designs I like to get the most performance out of her that I can.
      >
      >
      > last question, for today anhow, does anyone know the correct size and pitch prop to match the boat and the 2gm? This boat came with a three blade prop which i think is incorrectly matched to the boat. Again, the old owners used the diesel very little. During the delivery, we had to fight some really strong head winds and seas. The diesel cant reach is max rpm of 32-3400 and if really pushed sends out black smoke. I am new to diesels but my studying tell me
      > that this is and indication of the boat being overpropped. (All of the filters are clean, and I had the old diesel pumped out and the tank cleaned as well)
      >
      >
      > Thanks to all for your advice to this big boat newbie!
      >
      > < div>JP
      >
      >
      >
      > On May 12, 2011, at 12:42 PM, John wrote:
      >
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      >
      > Regarding the rudder bearing(s), please note that eliminating the play in the rudder is a little more complex than replacing the lower bearing.
      > My case in point: I dropped my rudder a couple of years ago with the intent of replacing the bearing because of the "slop" I could feel. After looking at the assembly I said "why and I doing this" I mea sured the ID of the delrin sleeve and the OD of the stainless ring on the rudder. Well 0.006-0.010" clearance for a journal bearing is ok with me. And there's very little potential for failure here so I put it back together.
      >
      > The biggest issue is the distance between the top bearing and the lower bearing and just how "true" the rudder shaft is. In order to eliminate any play the shaft has to be true and the top and bottom bearings aligned. If one feels different resistance when you turn the wheel one way and then the other, chances are the shaft isn't true and/or the bearing are not aligned
      > Replacing the bottom bearing is a pretty big (read expensive) job. If you want to do this for peace of mind feel free. If you want the best possible solution the rudder shaft needs to be turned up. This will take a pretty special piece of equipment and machine shop that can do it (read more expensive) then the lower bearing can be replaced and the top bearing replaced or at least floated in. If your biggest worry is the rudder falling out or breaking, fear not this is one of the strongest rudders I've ever seem . Now the weak link, there always is one. The only thing holding the rudder in the boat is the bond between the sleeve at the top and the fiberglass post and the single bolt going thru them. Personally I drilled thru and added another bolt. I also adjust my steering cable to be just tight enough and apply a light press on the packing gland. I do feel a slight a difference when I turn the wheel meaning my rudder shaft is not true but it spins very feely. I've had other drivers tell me "for a wheel steering the boat has great "feel"
      >
      > Sail Fast
      > John
      >


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