sizing replacement spreaders

Discussion in 'Sailboats' started by davisr, Sep 21, 2011.

  1. davisr
    Joined: Sep 2011
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    Location: Charleston, SC

    davisr Junior Member

    I must replace the OEM spreaders on my Ericson 25. These OEM spreaders measure 3 in x 7/8 in. OEM parts are no longer available.

    I've communicated with several spar manufacturers, all of whom have advised me to buy spreaders that are considerably smaller than the originals. They have all said that the appropriate replacement spreaders measure 1.875 in x 3/4 in. All have asked me the length of my boat. They have not, however, asked me anything else about my boat or rig. It seems, therefore, that their hasty answers to my questions on the telephone are based on generic tables.

    As I understand it, the moment of intertia specs for any given spreader indicate the strength of the spreader in terms of its resistance to twisting, and thus failure. Perhaps, though, I am misguided. At any rate, would anyone mind pointing me in the right direction as far as a book or article that will allow me to calculate the proper replacement spreader size for my boat.

    I'm clearly not a designer or builder, but I do like to understand how everything works on my boat.

    Thanks,
    Roscoe

    Ericson 25
    Charleston, SC
     
  2. PAR
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    PAR Yacht Designer/Builder

    Are your spreaders aluminum tubing extrusions with end fittings? If so, just buy the appropriate diameter and wall thickness (T-6) and change over the fittings.
     
  3. davisr
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    davisr Junior Member

    The OEM spreaders are foils. The main problem is that the cast aluminum brackets are a known weakness on the Ericson 25 and Ericson 27, but there is also the fact that one of my spreaders is worn thin on one side from repeated chafing from one of the old wire halyards.
     

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  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Considering your rig and hows it's set up, you don't need foil shaped spreaders, Roscoe. Have your tried Dwyer Mast?

    The 3/4" x 1 7/8" is the logical and cost effective choice for you. The next size up is a welded part and over 5 times as costly (hence the reason for the 3/4" spreader). 1" x 3" extrusion would be much strong er then you need, cost aside. I'd be inclined to go with a round tube and socket, though prices for these are similar to the foils (around $35 for a 32" spreader)
     
  5. davisr
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    davisr Junior Member

    Dwyer is actually one of the manufacturers that I contacted. I heard quite a few good things about Dwyer on the Ericson Yacht Owners forum. I myself, however, did not have a good customer service experience when I called up there a few weeks ago. Maybe it was just the wrong time. At any rate, the person on the phone seemed surprised/irritated when I asked him to supply me with the specs on the two spreaders you describe. I tried to explain to this person that the OEM spreaders (3 in x 7/8 in) on my Ericson were close in size to the large Dwyer spreaders (3 in x 1 in). Therefore, I was trying to understand why the medium-sized Dwyer spreaders (1 7/8 in x 3/4 in), as per his recommendation, were the appropriate replacements. All he did was repeat to me that the medium-sized spreaders were the right size.

    The Ericson 25 is good bit heavier than many other 25 foot boats, so I've been working under the assumption that Bruce King put these beefy spreaders on the boat when he designed her. Maybe, though, these spreaders were just overkill. I respect the opinion of professionals such as Dwyer who've been in the business for many decades, and I respect the opinion of the designers on this forum. I'm just trying to understand, from design or engineering perspective why down-sizing from my OEM sized spreaders is smart move.

    Thanks for the help in this,
    Roscoe
     
  6. Paul B

    Paul B Previous Member

    The OEM spreaders are WAY overkill, assuming they were OEM and not a retrofit. I think every sparbuilder you contact will tell you the same thing.

    Just as an example, a Catalina 27 is much heavier and stiffer than your boat. Yet the spreaders are simple 1.25" tubes.

    I see a bigger problem for you in your photos. Those cast brackets are junk. Worse, the butt end of your spreader is sitting on that blob of weld. The entire butt should fit flush against the mast wall or spreader base to spread the load. Hopefully the load isn't being taken by the bolt in shear.

    I'm sure you are going to trim the bolt flush with the end of the nut at some point.

    Trash the wire halyards (no more meathooks). Modern line is good for the job. Be sure to change the sheaves in the mast to match the line.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Paul makes several good points, Roscoe. The spreader sockets employed on your boat, were also the same sockets used on the 27 and other larger, heavier boats. This is a common practice and saves costs across several models, having common fittings. The cast units were the low end of the offerings pole when the boat was produced, now, as I'm sure you know, are junk.

    The 1 x3 foil from Dwyer has two cast fittings, with the inboard end having a built in pivot welded on. This forces you to use a much more expensive tang and the spreader itself, is either the stock length or has to be custom fitted (with it's slotted end cap). This is why it's $185 bucks just for the damn spreader.

    I'm not sure you rig needs to have it's wire replaced with line. You have enough windage there to not warrant the foil spreaders, nor the advantage of Spectra (or what ever) shrouds.

    You need spreaders and the 3/4 x 1 7/8 foil will do for a lot less. Save the money you don't spend, for a well setting main or a new headsail.
     
  8. davisr
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    davisr Junior Member

    Thanks Paul and PAR for all the advice,

    I feel much more comfortable going with the medium-sized (1 7/8 x 3/4) Dwyer spreaders. Nice price. I really didn't want to have to pay for those large-sized ones, which are so much more expensive.

    As far as the OEM issue is concerned, those speaders/brackets are indeed original to the E25 and E27. The spreaders themselves seem to be of excellent quality. The cast brackets, on the other hand, are just the opposite. The weld you see in the picture is from a crack repair that a prior owner performed. At least one E25 owner has experienced a dismasting on account of a cracked bracket.

    I've already replaced the masthead sheaves in order to transition from wire-to-rope to all rope halyards.

    Thanks for your expert advice,
    Roscoe
     
  9. Paul B

    Paul B Previous Member

    If you are worried about the smaller size at all you might want to consider the Kenyon "thick walled" version of the spreaders in the 1.88" x .75" size. They are about 1.5x as "stiff" as the normal ones.

    I guess you've already priced the whole thing out including the new spreader bases for the smaller spreaders. The thick walled versions will probably add a bit to the cost, but maybe worth it for your peace of mind.


    Nice to see you understood my comment about the halyards and did not think I was talking about using rope for standing rigging.
     
  10. davisr
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    davisr Junior Member

    Thanks Paul,

    Kenyon happens to be one of the other manufacturers I've been considering. There is an Ericson 27 owner who recently replaced his OEM spreaders with the Kenyon SP2.2 spreaders (1.88 x .75 in), which appear to be the thick-walled versions of the SP2 spreaders (1.88 x .75 in) to which you refer. Rig-Rite/Kenyon, in a recent email to me, indicated that the SP2.2 spreaders would also be the appropriate replacement spreaders for the Ericson 25.

    I don't know what the wall thickness is for the Dwyer DH2503 (1.875 in x .75 in) spreader, since the specifications are not available online. I do know, however, that there are differences between the Dwyer spreaders and the Kenyon spreaders in terms of the way they are joined to the mast. The Dwyer spreaders are joined by means of steel brackets, which are supported by a single compression sleeve. The Kenyon spreaders, on the other hand, are joined by a solid spreader bar and reinforcing plates.

    I've actually been trying to figure out whether one method of joinery (bracket/compression sleeve or spreader bar) is superior to the other. I've posted questions in this regard on several other forums, and I have been surprised to find that these questions have generated little attention or commentary.

    Thanks again for the helping hand,
    Roscoe
     

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  11. davisr
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    davisr Junior Member

    For the sake of those who may wish to know the difference between the Dwyer spreaders and the Kenyon spreaders, here is what I know, based on information I received from Dwyer today:

    The Dwyer DH2503 spreader is specified to have a wall thickness of 0.75 inches.

    The Kenyon SP2.2 spreader is likewise specified to have a wall thickness of 0.75 inches.

    Therefore, the Dwyer DH2503 has the same wall thickness as the thick walled version of the Kenyon, i.e., the Kenyon SP2.2.

    This means that the primary difference between the two is method by which they are joined to the mast. Dwyer uses a compression sleeve. Kenyon uses a spreader bar. There are big differences in price. Complete replacement set for Dwyer (two spreaders and two stainless brackets) is about $200. Complete replacement set for Kenyon (two spreaders, aluminum spreader bar, and stainless reinforcing plates) is about $400.

    Unless there is any compelling reason that the spreader bar set-up is far superior to the compression sleeve set-up, it makes good sense for me to go with Dwyer.

    Any suggestions to the contrary before I purchase the Dwyer spreaders?

    Thanks,
    Roscoe
     
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  12. PAR
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    PAR Yacht Designer/Builder

    Nope, you look to have a cruiser there, so the rig shouldn't be as highly taxed.
     
  13. davisr
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    davisr Junior Member

    PAR,

    Thanks for your advice that the Dwyer compression sleeve set-up is the better choice for my cruising-oriented boat. I look forward to spending the $200 I'll save on a more pressing matter - a new headsail.

    If you don't mind, though, I would really be interested in hearing your thoughts, as a yacht designer, on the benefits of the spreader bar set-up. I've looked in Don Casey, Nigel Calder, John Vigor, Brion Toss, and Daniel Spurr, and I've found no discussions of spreader bar benefits. Granted, these are not yacht design books. From a layman's standpoint I would think that the spreader bar would provide much more strength to the rig, but that's just my guess.

    Best regards,
    Roscoe
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The spreader bar is a compression post, designed to transmit loads through the mast, rather then to the mast. Yep, it's stronger and seen on higher preformance applications.
     

  15. Paul B

    Paul B Previous Member

    <removed potentially insulting comment>

    For example, a spreader bar is not a compression post and transfers the compressive loads of the spreaders to the mast wall the same way a welded base or a mechanically fastened base do.

    I think any of the commercially available spreader bases will work for your application.

    A welded-on spreader base is often seen by cruising folk as a "strong" attachment. However welding on the lug anneals the metal.

    A mechanically fastened base does not anneal the metal. It does add dissimilar metals and corrosion issues to the mix. For spreaders of the size we are discussing there are different weldments available. The Dwyer type looks to be the type where a lug slides inside the spreader. There is also the old Kenyon Etchells style, where the spreader sides into a socket. I think this is a stronger design. It is more expensive.

    The spreader bar is my favorite base for alloy rigs. It is a basic cantilever when you consider vertical loading and rotational loading on the rig. Depending on your mast wall thickness you might have to add a wall doubler, especially if you hang the shrouds off of the spreader bar (photo 1 below). If you have a modern tube and hang the shoud off the mast wall below the bar you will generally not need a doubler (photo 2 below). They can be a pain to assemble, depending on the amount of dihedral. Be sure your alloy bar has SS chafe bars fore and aft if you run wire halyards.

    For a refit like you are doing the mechanically fastened weldment is as good a choice as any.
     

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    Last edited by a moderator: Sep 29, 2011
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