Missinginaction update and a question or two

Discussion in 'Fiberglass and Composite Boat Building' started by missinginaction, Dec 26, 2007.

  1. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    It's been a while since I posted, but I've been doing a lot of reading. During the fall I had the time to do some additional disassembly on my 1973 Silverton. I'll post a few pictures below. I'm looking ahead to spring and beginning to reassemble this boat in earnest. In preparation for that I have a couple of questions for some of the more knowledgeable among you.

    As you can see I have the running gear out of the boat and the floor forward of the engine compartment has been removed. As soon as the weather breaks I'll remove the dryrotted engine stringers. I'm curious weather any of you have had much experience using foam as a core material for the engine stringers. I've read that some use foam such as Divinycell 80 for stringers, covering them with 4 layers of 28 oz. double bias stitchmat. This is a more expensive proposition than simply using 3/4 marine plywood as a core material. Can anyone advise me weather the foam core approach is worth the additional cost?

    The other photos show what was left of the stuffing box and the shaft log. As you can see the nylon compression spacer at the bottom of the stuffing box is pretty much worn away and the propeller shaft has a ridge in it. I believe that the ridge was caused from an out of alignment situation that caused the prop shaft to wear on the nylon compression spacer. The good news was that the shaft alley inside the shaft log was free of any wear. The shaft log is fine, the shaft has a little wear around the strut, but not much and the cutless bearing is in good shape. I'll replace the cutless bearing anyway.

    How do I determine if this boat needs a new shaft? Is the wear that occured inside the stuffing box enough to require a shaft replacement?

    I'm considering replacing the current stuffing box with a mechanical seal such as the PSS Shaft Seal. This approach would seem to solve two problems. The first being the issue with the wear on the existing shaft. The second being the fact that this v-drive is very difficult to service below the engine. Space is very limited.

    Please let me know what you think. As always thanks in advance for your interest and advise. Hope you all had a Merry Christmas!

    MIA
     

    Attached Files:

  2. Kay9
    Joined: Oct 2006
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    Location: Central Coast Oregon US.

    Kay9 1600T Master

    Well shaft diameter is the call for a new shaft. But at the very least. I would get that one turned smooth again.
     
  3. AroMarine
    Joined: Jul 2005
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    Location: Atlantic City NJ

    AroMarine Junior Member

    Foam core for stringers is a valid stringer replacement many boat mfgrs use them successfully but you need something more that a few layers of glass to bolt into. You can imbed aluminum plates in the glass, build long aluminum frames that spread the bolt load, or use wood. Costs can be pretty high for aluminum engine beds. This is a good place not to skimp. If you use plates for your size engines 1/2 thick is plenty. Drill and tap the bolts for your isolators. Fiberglass and wood also good choice l
     
  4. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Based on the feedback I'm getting so far I'll probably replace the shaft.

    Thanks for the feedback guys.

    I'm still not certain how I'll tackle the stringers. I just want to be sure that I do it once and correctly. On of the problems this boat had was misalignnment of the prop shaft. Looks to me like that occured as the stringers deteriorated, allowing the engine to vibrate as load was increased. Fortunately, the previous owner just slowed down as the vibration problem increased. For the last couple of years before I bought the boat he rarely took the boat over 1800 RPM (which was still displacement speed). I'll reinstall the 302 CID Ford engine for now and see how the boat performs when she's back in the water. If performance is still lacking I can always upgrade to a stronger powerplant so long as I've built proper engine stringers and beds.

    Regards & have a happy new year!

    Missinginaction
     
  5. Kay9
    Joined: Oct 2006
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    Location: Central Coast Oregon US.

    Kay9 1600T Master

    You know the vibration could have been caused by the shaft being warped. If you are replacing the shaft, then no sweat, you got it beat, but it might be worth checking out, that way you KNOW what the problem was.


    K9
     
  6. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    It's certainly possible that the shaft was warped. Based on some preliminary contact with some people who sell replacement shafts it seems that attempting to refurbish the existing shaft would not be cost effective. Since it's only about 5 1/2 feet in length it's not an extremely expensive proposition to replace. Looks to be in the $400 - $500 range for a quality SS shaft. I'm thinking that it would be a good idea to send the shaft out to whom ever I decide to have make up the new one. I'm sure they'll be able to diagnose what caused the wear better than I. After all these people see prop shafts all day long.

    Based on what I can see since I removed the forward floor & sounding the engine stringers I'll wager that things were so far gone down there that the engine was able to move considerably when anything close to max power was applied.

    Either way replacing the whole "shootin match" is certainly warranted given the age and wear on the parts involved.

    Regards,

    MIA
     
  7. Kay9
    Joined: Oct 2006
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    Location: Central Coast Oregon US.

    Kay9 1600T Master

    I think thats a great idea. Glad to hear it isnt overly expensive.

    Good sailing.

    K9
     
  8. Frosty

    Frosty Previous Member

    If your engine has been moving exessively then thats your shaft wear. The stuffing box should be rubber tube mounted and allowed to move with the shaft. Fore some strange reason I have seen some boats with them being rigid. If not your shaft will wear very quickly. Not a fan of PSS seals.

    Your shaft could and should be reversable ( Identical taper cut at both ends) You can get 2 lives out of it .

    A 5 foot shaft should be 2,1/2 inch at least. I think 400 dollars would be a bargain. I could'nt get that cut here for that price.
     
  9. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    hi Frosty,

    This is just a 1 1/4" shaft connected to a 5 liter Ford (302 CID).

    It's just a single taper shaft.

    The stuffing box was flexible, but it appears that over time the engine misalignment caused the shaft to ride on that nylon compression spacer at the 'bottom" or aft end of the stuffing box (the part of the box that the flax rings bottom out against when you tighten the compression nut). That misalignment caused the wear that I see on the shaft. Also, the shaft is not stainless, but appears to be some type of bronze. I don't see this type material being used anymore and wager that it's relative softness compared to stainless steel has made it obsolete. Or maybe the stainless is just a better and less expensive solution.

    One last piece of information. When I removed the engine I discovered a corroded motor mount bolt. The bolt looked secure, but was deteriorated inside the mount where you couldn't see. Only having three corners of the engine securely attached to the boat would certainly cause problems. Fortunately this is all easily addressed.

    The reason I asked about the PSS type mechanical seals is that the stuffing box on this boat is very difficult to service with the engine in the boat due to the v-drive. I'm 52 and 6' tall 175 lbs. I'm still pretty flexible for my age and thin enough to get in there, but it's an awful place to try to move your arms, let alone do any work. I'm thinking that a machanical seal would require less periodic maintenance in that area.

    Thanks for your feedback,

    MIA
     
  10. AroMarine
    Joined: Jul 2005
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    AroMarine Junior Member

    I have worked on many repowers using PSS seals much better than stuffing box. Your rubbing in the stuffing boxes can be from a couple of areas. Hard to see but it did not look like any of your mounting brackets moved. So the wear could be from deteriorated isolators, poor misalignment after some engine service, the board under the strut looks like it was a replacement and not factory poor strut placement after an incident. Anyway drill a couple of samples from your stringers those old silvertons held up pretty well. You probably do not have to remove those stringers. If there is rot around the bolt placement areas then you can cut out one side of the stringer and replace some of the wood and then reglass. You need solid materials for the bolts. The height of the stringers and the glass should be no problem for a single v8 and vdrive. What you might need is a thwart between center two and outboard stringers.
     
  11. AroMarine
    Joined: Jul 2005
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    Location: Atlantic City NJ

    AroMarine Junior Member

    Sorry about the first post from me I did it before looking at your project. Also you can do the thwarts with structural metal ie aluminum or steel .
     
  12. Frosty

    Frosty Previous Member

    If your v drive is bolted to the engine and not seperately bedded to the boat, the shaft will push up on the gearbox/engine and that can push it out of alignment.

    No ammount of static alignment will account for this.

    A thrust block of the V drive itself or a seperate thrust block would eliminate this.

    Thrust blocks such as those made by Halyard are a wonderfull way of going about re shafting. The shaft will also be slightly less expensive due to it being shorter. This final installation makes for softer mounts and a smoother boat.

    I make my own deep sea seals with a bronze housing holding 2 simple lip seals and an oil bath in the middle. The oil bath is fed by a head of say a foot. I have had no trouble with these running at 1000RPM +

    If they fail it will only drip,--
     
  13. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Thanks for the reply Aro,

    From what I've discovered thus far those stringers are pretty well shot, but they may be less deteriorated away from the limber holes and the joints where they join the floors. There was evidence of resin starvation where the joints were (lot's of air space where moisture entered).

    I'll also look into the idea of thwarts. I'd not thought of that and the stringers run for quite a distance in the engine compartment with no lateral support.

    Regards, MIA
     
  14. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Thanks for the reply Frosty,

    It's interesting what you wrote about the thrust issue, with the prop shaft connected directly to the v-drive. That is the situation here and I often wondered about the thrust from the prop pushing the drive/transmission and rear of the engine (which faces the front of the boat) up.

    I'll attach a photo so that you can see the set up with the engine in place. This view is from the bow looking aft at the drive. The mount on the right contained the broken bolt.

    I'm not sure weather some type of thrust block is practical in this application as there is little room forward of the shaft log (between the shaft log and the v-drive coupling). I'll have to do a little research on this.

    By the way, I envy you being the Thailand. The outside thermometer here reads 0.6 degrees F.

    Regards,

    MIA
     

    Attached Files:


  15. Frosty

    Frosty Previous Member

    Well ive never been to New York, its about 75 degrees this morning -- a bit nippy!! Ive seen the movie 48hours -- is that New York?

    Ive never seen mountings like that before, they don't look up to the job to me,-- let alone the bits of plywood shims.

    Your thrust goes into the thrust bearing in the gearbox which pushes up the gearbox/engine, mountings and finally the boat. If the engine moves and you have a solid shaft log it will damage the shaft,--obviously so.

    Are you sure there are no provisions to place 2 more mountings on the gearbox itself. Having a 6 mounting configeration is possible and advised by some Yanmar installations. I would be surprised if there was'nt. Something to consider!!

    Orange County Choppers,--- I watch that every day, Thats New York isnt it?

    By the way are those rubber hoses your wet exhaust?---Way too small.
     
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