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Thread: STRONGBACK DISCUSSION etc.

  1. #46
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    mast support beam

    The beam in 198 has a very slight bow in it, barely noticeable when eyeballed, and less than an eighth inch at the corners when measured with a straight edge, is that enough to worry about or should I do some refurb on it?

    Did search, but while info on swapping and re-enforcing it was abundant, I couldn't find anything to indicate what was acceptable.

    Also, are replacement lenses available for the stern light? mine has everything but the lense itself, looked at the other lights, and it's the same style (hemisphere about 1-1.25" diameter) the light's in good shape except for the missing lense so would prefer finding a lense if possible.

    Thanks
    Ken.

  2. #47
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    Search on "strongback" for answers. Manual has complete discussion.

    Sea Dog makes 1" replacement globes that fit the Pearson hardware. Plastic, however, not glass. Cheap, so you can purchase extras . . .

  3. #48
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    compression beam possible quick fix.

    Hope that 'Bill Ariel 231' will post here. He is more practical and less wordy than I.

    The support beam has a bow in it, of course, that more or less conforms to the curve of the coach roof. The support beam supports the composite fiberglass/balsa laminate that the mast step and mast sits on.

    I believe that over time there is natural settling and shrinking that happens even though the wood of the beam is still in good condition. If you have opening across the top it may merely be a condition of age. Even bad original fitting that has opened even more.

    Test the beam for soft spots especially in the center. If you have rot, that is a more complicated problem. It's another diagnosis. A repair such as described below cannot be fudged on a rotton beam. Replacement.
    Check the curve of the roof outside to see if the mast rigging has pulled the mast into the roof any. Flattened it.
    Because the navigation wires (used to) go into the interior through a hole under the hollow of the mast, rain water may have rotted the balsa under the mast-step in the composite. Check the roof if there is a slightly more localized depression. Needs to be fixed.
    The coach roof should have a fair curve to it. Anything else requires a change in plan.

    If you are lucky to have the mast sitting on a nice round cabin roof without any flattening (you may be the first!) then you can go about finding a way to fill the narrow space between the beam and the coach roof inside.

    When you decide to go full monte on this fix, you remove the deck mast step by taking out the two 1/4" (#16) bronze flat-head lags that clamp it to the beam inside. Could be problem. When mine came out on 338 the cabin roof nearly returned to its original molded curve. And the narrow space inside opened up considerably more.

    Pearson fudged the fit when assembling the Ariel as they used the mast support beam to clamp in the forward end of the cabin liner. That means that any fix cannot be attempted from the cabin - but from the V-berth area. It also supposes that the beam didn't fit quite as snug as it was supposed to. The beam may be tight against the liner on plywood bulkhead side but not quite so tight on the V-berth side.

    You cannot fix the space problem with the mast rigged and pushing down on the roof. You can fix it when you RETURN THE COACH ROOF TO ITS ORIGINAL MOLDED CURVE by temporarily relieving all the pressures on it. The mast has to be taken down.


    The coach roof has some rounded dimensions that isn't really compatible with flat carpentry.
    Look at the problem with a few options in mind. You could for example bandsaw and shape to fit a single piece of wood that you glue into the space. That's the best way.

    One uncommon way to consider.
    Clean, scrape and remove paint, silicone snot, fillers that are in and around the space. You are working from the V-berth side. And you are deciding what you can do that will keep the roof totally supported.

    I have had success using wood filler pieces and epoxy mishmash (laminating epoxy, fumed silica as thickener, and 1/4" chopped fiberglass strand) a kind of hairy pudding.
    Wet the inside area with plain mixed epoxy and wipe it up best you can. Use terry toweling pieces stapled to thin battens. Get this 'primer/bond coat' dry as you can after wetting so that your mishmash won't mix with it and loosen and sag out of the joint.
    Slide your wood filler pieces in slathered with gobs of pudding. You will have done a dry run so you know they fit good and where. The more wood, the less expensive glue. Longer pieces might even add a little strength to the beam.
    Make sure you are stuffing the cavity all across the top.* You may be using some shim/wedges to get a tired coach roof to curve back properly - no forcing - you don't want to put anything under tension here - it will pull apart later - just enough.
    I would shim the coach up using the beam in the center if necessary. Or prop the coach roof fair next to the beam with some 1X2 or 2X2 from the berth or sole. They'll be in the way, tho.
    You might have a special shim or two that can be left epoxied in there. Use durable woods like fir and mahogany. Don't leave anything sticking out.
    Once it's gooped and filled, take paper towels and remove any squeeze out and runs.
    Clean up with alcohol so that there is minimal sanding prep for the next step.
    This is a quick and dirty fix that allows the carpentry to be kept in place. It will only work if your diagnoses was correct.
    Assumes that your beam and bulkhead are in good shape. That the composite under the mast is also OK. And the mast step itself.
    It can be done this way, but I don't really recommend it. I would do a classic reconstruction if warrented - and do it right.
    __________________________________________________ ________________________________________
    * To control the extent of epoxy being pushed into and through the joint (the juices may run down the cabin side of the beam and bond the cabin door trim )- use cheap polyethylene foam 'backer rod' from your concrete store in the back of the space (seen from the V-berth). It isn't hard rod, it's soft yet firm foam you can stuff into tight places to create a dam. When you push in the wood filler pieces, you want the epoxy pudding to kind of billow out. There's going to be a little waste.
    __________________________________________________ ________________________________________


    BUT it's hard to know exactly what you got there without some photos. Good luck.
    Last edited by ebb; 10-01-2008 at 09:02 AM.

  4. #49
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    Ken

    I agree photos would help here. It sounds like a couple things may be going on here. I recommend a through check of the beam, the columns that support it and the deck core directly below the mast step.

    Beam: is the beam compressed in the middle where it has been drilled out for fasteners and wiring? (mine was) Is it compressed where it crosses the columns at the passageway? It is supported by roughly a 2x2 at that point. Are there any tell tale fractures across the grain in either area? The only way to tell is to grind off the paint to see. If the beam has a small depression where it meets the column (or none), and there are no cracks and no rot then Ebb’s epoxy fix will work just fine.

    If there are cracks or signs of Rot… reach for the Sawzall. The Beam is held in place with 3 to 4 wood screws (port and stbd) installed from the cabin side (hidden by the formica). I elected to cut them flush on the vee berth side. Making a new beam is easy if you have a band saw, not much harder with a recip saw and an angle grinder. If there is any doubt about the beam, it is worth the piece of mind to change it. Although the deck beam doesn’t look like it can take it, the design load for the mast step is often a high fraction of the boat’s displacement. (refer to Brian Toss’ book for the test case at 45 degrees heel on a boat’s standing rigging). In Periwinkle’s case (A-231) the beam had both rot and a fracture in the middle of the beam. The replacement was a white oak beam glued up from two planks, rough cut to a paper template of the old beam and trimmed to fit with a grinder. My replacement beam is now screwed in place with wood screws thru the bulkhead at the original factory location. Installation of the beam followed Ebb’s suggestion with the beam buttered in thickened epoxy before final assembly. One alteration I made from the factory install was to relocate the mast wiring to a tube on the stbd side of the mast mast step. After fabricating a new mast beam I couldn’t bring myself to drill a big hole in the middle of it for a wire chase.

    Columns: Compression at the top is possible, but I haven’t seen it or any photo’s of pearson tritons and ariels with that symptom. See if there is any rot top or bottom that might indicate the column and the bulkhead moving down. This would be bad but again there is easy access on the vee-berth side to affect a repair.

    Deck: While you are there, make sure the deck under the mast step doesn’t need to be recored. I’ve pulled my mast step twice. Once for the restoration and again when the deck core under the mast step failed. I believe the deck directly under the mast step should be solid ‘glass (or at least plywood). The original Balsa on mine was both crushed and wet when I opened the deck after 4 years of service. No issues since replacing the core with glass for a couple inches around the mast step. I recommend checking the deck core while all of this work is in progress because this is an easy extra step while the mast step is out.

    Good luck
    bill@ariel231
    Last edited by bill@ariel231; 09-30-2008 at 06:36 PM.

  5. #50
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    Wink Mast Intrusion

    Right on Bill!

    Shouldn't have to add anything except to emphasize this: Remember, there are four things that could be happening to the support beam.

    1) It could have contracted rot through the electric wire hole and can no longer hold its curved shape. (338's beam was bandsawn white oak and showed no rot.) White oak doesn't like to rot.

    2) The composite sandwich of the molded roof could be deteriorating because the core balsa is rotting from water entering the same wire hole. It compresses under the mast when there is no support inside.

    3) The wood parts all together may have 'settled' and moved a little over the decades.
    [This was 338's main problem when first tackled. I thought the beam had gone bad - but when taken out was perfectly OK] The composite core had some deterioration but imco the actual problem was the mast's irresistible force down on the beam and the beam not able to keep its original position.
    Forensics conclude that since NONE of the parts (beam, angled braces that terminate on the V-berth tops, doorway framing) were glued to the plywood bulkhead but just mechanically screwed on... it all over time had gotten tired making it easy for the mast to compress it. While the mast contributes constant pressure, I'd guess that sailing the boat compounds the downward pressures.
    The bulkhead upon which the strongback system is dependent is only 3/4" exterior fir plywood* that is tabbed to the boat ONLY at the hull under the deck. The whole top with the significant doorway cutout is free to move.
    (With the exception of the two lags that hold the step in place that go through the deck into the top of the beam. And maybe the uppers' chain plates held by the deck!)

    4) Constant downward pressure of the mast and step on the coach roof causes the beam to deflect, or to appear to deflect. The white oak beam is only 4 feet long - and if it's healthy no way in hell or high water will it flex. You might find deterioration of the fir plywood right next to it but the beam will be fine. (This is a guess -ANYTHING is possible.)
    The round wood laminated step outside might also be deteriorating.
    338's is still going strong.

    Problems seen at the beam inside (the trim of the doorway sagging is common) could be one or a combination of these symptoms. Examine the parts and with what other Ariel skippers have found figure out what might be going on.

    Imco if you are going to really fix this common aging problem you have to make sure that the coach roof under the mast can never deflect, never flatten, and always keep its original molded shape.
    As Bill suggests all the interior structure under the mast should be renovated into a monocoque, a glued and screwed structure with the bulkhead tabbed everywhere, all round, to the boat. (Naturally, you won't tab onto the cabin liner!)
    The upper shrouds thru-deck chainplates would also benefit from a more secure bulkhead. The ply where the uppers' chainplates come thru the deck no doubt is also deteriorating from water leaking in. Check this also.


    __________________________________________________ __________________________________________
    DOUBLE BULKHEAD idea for the traditional interior.
    * A better structure would be to add another 3/4" ply bulkhead to the V-berth side of the beam and braces. Make it into a kind of a boxed truss. The all important 'compression' beam would then be supported on both sides and transformed into a true bridge.
    Instead of it all cantilevered off the one wall - which is the problem.

    Movement of all structural pieces would be locked forever between the bulkheads and all downward force from the mast taken evenly to the hull by both bulkheads. NOTHING COULD MOVE. The mast load would have a wider 'point load' spread on the hull - where a single loaded bulkhead often deforms a glass hull. It's the hull that takes all of the mast load.
    Could scroll openings into the new bulkhead (maybe now even both) to gain back some lost space and keep closed areas ventilated.

    This begs the question: why go to the trouble adding a whole bulkhead when a large one piece GUSSET that spans the whole doorway on the V-berth side MIGHT get the stiffness and immobility needed?
    The original Pearson SO-CALLED bulkhead that the compression beam is sort of attached to is actually in THREE pieces: the two major pieces on either side of the doorway and a FILLER piece over the door that the door trim hides.**

    (This is another unacceptable (imco) cheat on the part of Pearson because it don't add a MODICUM of support for the mast beam.)
    It would have been much more shippy if the doorway had been top rounded like the Brits did in the Contessa 26 creating more truss and panel support for the beam. But then the carpentry trim and the door would have been beyond the capabilities of Pearson carpenters - would have had to be out-sourced and added another $200 to the price of an Ariel.

    Instead of a complete second bulkhead:
    Adding a crosspiece that goes completely across & down a little ways ( or even to the V-berths) is something to consider. Especially if you are racing your Ariel. Also if the bulkhead is being redone by, say, the removal of the disgusting imitation wood formica on the accommodation side - a cross TIE of plywood or mahogany across the top could be added on this side as well that would provide extra support for the beam. Glue and screw.

    After the space above the beam has been addressed and filled or shimmed, adding a one piece gusset over the door in the V-berth that fits the coach-roof curve AND a side to side cross-tie in the cabin would stabilize the compression problem imco.

    [It's my opinion that a metal strap across the top of the doorway does not fully solve the compression beam sagging problem.]
    Point is
    there are any number of fixes possible.


    Even for a completely altered interior:
    1) Water intrusion HAS to be fixed.
    2) Rot has to be removed and fixed. Especially in the composite. It's pretty easy. 338 now is solid stitched mat and epoxy instead of balsa.
    3) Coachroof must be full rounded, fully restored or fully upgraded.
    It gets tremendous strength by being a true arch. If flattened, stress is concentrated right under the mast instead of the point load being spread to the curve of the arch. The beam inside is meant to preserve the coach-roof arc. The mast load should be held by the whole beam - not just the middle.
    Wires should probably exit the side of the mast a half a foot or more above the deck and enter the interior thru one or more thru-deck glands near the mast. Thru-holes from the mast interior should be sealed off. It's no place for a hole because there is no access to a problem there.
    OK, got carried away again!!!!! Apologies


    I AM just throwing logs on the fire for discussion.
    Wouldn't it be great if a concensus could be reached here?
    that would provide an easy, satisfying and strong fix that ANYBODY with a new Ariel could use to repair the MAST SUPPORT BEAM PROBLEM./././
    __________________________________________________ ___________________________________________
    **This major fumble was left out of Everett's biography.
    Last edited by ebb; 10-04-2008 at 05:18 PM.

  6. #51
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    Merging Threads

    This thread will be merged with the strongback thread tonight.

  7. #52
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    Appreciate the info, I'll get some pics today.
    The bow is a very slight downward bend, not to the curvature of the roof. No space above it, it sits flat against the coachroof, also can't detect any rot, and the wiring comes up on deck beside the mast, not through the beam.

    I'm in construction and do a lot of post and beam building and reconstruction, Kept wanting to call it a lintel, but knew that wasn't the nautical term.....

    Ken.

  8. #53
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    Good news, the downward bow was all in some trim he had wrapped the strongback in, spent an afternoon peeling the trim off, Put the square up while it was out and found it was nearly perfect.

  9. #54
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    that is good news... on to the next project

  10. #55
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    I found out the Sea Dog clear replacement lens (model 4000121-1) does NOT fit. Too big.

    http://www.defender.com/product.jsp?...20403&id=64846

    This guy is supposed to sell replacement fixtures and globes. Not in the catalog. I haven't called him yet

    http://www.bronzeblocks.com/
    Last edited by commanderpete; 10-07-2008 at 06:47 AM.

  11. #56
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    Commander to Ariel conversion

    The Commander has a compression post under the mast that transfers the load right to the keel. Only a knuckle head would want to change a strong and fool proof design like that!

    I'm kinda a knuckle head.

    In an attempt to create a roomy, private head with easy access I want to remove the compression post and put in a strongback, full bulkheads and a door like the Ariel. looking at the Ariel drawings I don't see how the load is carried to the keel. It appears that the bulkhead is relied on to carry and disperse the load. It looks like there is a vertical support on either side of the doorway, but I don't see anything under it. does it just terminate at the sole?
    The manual (pg 23)shows diagonal supports, but does not show how they terminate on the lower end. Is there any additional structure not pictured in the drawings?
    Attached Images    

  12. #57
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    How thw strongback was installed in A338 by Pearson

    C'227,
    Nice to see those two compared in drawings with each other like that. Thanks.

    You are correct on all points.
    I've gone on about this subject adnauseum elsewhere. But suffice to say that in the Ariel the bulkhead is part of the mast support system. There are the two posts that define the doorway - they go down to the hull above the turn of the bilge (screwed to the plywood bulkhead.)
    There are two cross braces on the Vberth side also screwed to the bulkhead that terminate on the Vberth plywood tops. And two more vertical braces that support the end of compression beam at the coachroof sides - also terminating on the Vberth. Across the top the compression beam is also screwed to the bulkhead. And held in place thru the top by two bronze #14s or #16s coming thru the mast pad, thru the composite deck, and into the beam.* All structural wood was white oak.

    The plywood bulkhead in A338 is really two halves with a filler across the top of the doorway and a filler across at the step up into the V-berth stateroom. There is no work done by either of these fillers. (FYI A338 has since been remodeled to remove the doorway.)

    The plywood "bulkhead" is tabbed to the hull ONLY
    and not to the under deck or the coachroof sides or overhead.
    Only the hull. And not across where one might expect a 'floor' to be in a wood boat - per your question.
    Originally the space between the bulkhead and the liner was stuffed with a factory supplied fabric covered foam tape.

    The compression beam load is ultimately taken to the hull via the half bulkheads (let's call them) on either side of the doorway. The compression beam is not supported in the center between the door posts. The door posts therefore are dual compression posts if you look at it that way. But they bear on the hull incidentally. In an upgrade a wider bearing pad would be cut in under these posts.
    __________________________________________________ ____________________________________
    *ANY upgrade or remodel imco, if you are working from the original Pearson model,
    should have all dimensional wood members GLUED and screwed to the plywood at the very least.
    But the Pearson model is very flawed.
    Last edited by ebb; 12-09-2008 at 05:49 PM.

  13. #58
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    A couple of points from an A-231 perspective:
    "The manual (pg 23)shows diagonal supports, but does not show how they terminate on the lower end. Is there any additional structure not pictured in the drawings? "

    Construction detail from A-231: A-231's diagonals terminate at the surface of the vee berth.


    "The plywood "bulkhead" is tabbed to the hull ONLY and not to the under deck or the coachroof sides or overhead."

    Construction detail from A-231: the original mast beam was buttered to the overhead with thicked polyester (the ubiquitous blue stuff). I did the same with thickened epoxy when i replaced the beam.

  14. #59
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    As a result of a bridge vs. mast accident resulting from a crew malfunction related to tabernacle operations in 2004 I needed to do some repairs to my mast base support system on my 1965 Pearson Ariel. For a more detailed discussion of this repair with photo documentation, please see my Ariel web page:

    http://www.solopublications.com/sailarir.htm

    Although like many other Ariel owners, I wanted my main bulkhead to be a strong as possible, it is worthy of note that after forty years of successive owners riding a Pearson Ariel hard and putting it away wet caused no visible deformation of the strong back as of the autumn of 2004.

    I removed the Formica on the aft side of the strong back and sanded both sides of the strongback. I chased a few cracks and voids, but those led led me to workmanship and assembly issues that resulted during construction forty years ago when my boat was built.

    I filled a few voids and strengthened a few areas. The bulkhead and strong back have served three owners well over the years. My somewhat destructive examination continued to show virtually no bulkhead damage Both professionals with whom I consulted did not feel that through bolting steel plates on either side of the strong back would be the best solution to strengthening the mast support system. In my boat there was no evidence of sagging in the strong back.

    Once the teak doorframe was removed, it was apparent that the horizontal beam above the door was level. One of the vertical frame members was actually vertical, but the other is not, so that the door opening is a lopsided trapezoid. Since the plywood opening is cut this way and there is no separation from the hull on either side or underneath, I must conclude that this “as built”, rather than “as failed”.

    Although the Main-salon-side plywood bulkhead panel was not glassed to the cabin liner, I could see over this panel to what appears to be a glassed seam between the strong back and the deck. This seam was solid and there was no indication of sagging or separation. The area above the plywood on the Main Salon side of the bulkhead looked fresh and solid. I came to the same conclusion by looking at the seam between the strong back and the underside of the deck from the V Berth side. Removal of the paint from the strong back confirmed that conclusion.

    The cracks that I chased and the voids that I discovered were probably left by the builders (the failure to wet out tabs holding key braces in place, voids in the fiberglass, (the use of AC plywood with significant internal voids, etc.). So I would have to say that my boat might have been both hastily built, but it was also overbuilt. The Pearson Ariel is sort of like a Sherman tank built by the low bidder. This is one strong boat, albeit one built somewhat strangely in places.

    Because it is conventional wisdom to strengthen the strong back, I contracted for reinforcement by a professional. My contractor installed unidirectional cloth and triaxial cloth. This was glassed onto the bulkhead and strong back in a sufficient number of layers to reinforce the strong back/bulkhead without drilling holes through it or installing steel reinforcement plates as have been used on some Ariels. This solution provided for the strong back to be glassed to the underside of the deck forward of the bulkhead and to the cabin liner aft of the bulkhead. When repairing the top deck, the new top laminate, bottom laminate, core, and cabin liner were reconstructed as an integral unit. Thus the strong back, cabin liner and deck now function as an integral unit. Thus there is no longer a void above the plywood section of the main bulkhead on the main salon side. This void was originally filled by that strange foamy wire-reinforced trim piece. That piece was glued into the void above the plywood. Those little wires are sharp and hard to remove.

    The longer bolts in the mast base that had been inserted in the foreword two holes were seriously bent as a result of the mast vs. bridge accident. The bolt holes for these bolt were directly above and ran through the stong back. They penetrated the strong back directly above the doorframe. Their securing nuts were captive inside the beam. Inspection holes were provided by the manufacturer in the bottom of the beam. Those holes were drilled completely through the teak door fame as well. The beam prevented the lower portion of the bolts from bending. In the accident, the bolts were pulled upward. The bends in the bolts occurred at the very top of the bolts. The angle of the force of the impact pulled the longer forward bolts upward, and the shorter aft bolts downward as the mast step plate rotated aftwards into the deck upon impact with the bridge. This effectively crushed the deck beneath the mast step. This entire area was rebuilt as an integral unit, and the forward boltholes were relocated.

    The cabin liner in the main salon was obviously distressed as can be seen in the images on my above referenced web page. Less severe distress was evident in the forward salon, but some cracking in the lower laminate occurred.

    The shorter bolts were driven down through the cabin liner causing the liner to crack and shatter.

    The cracks in the bottom laminate were removed by grinding, as was the paint on the central section of the strong back.

    Multiple layers of vinyl ester resin and fabric were added to the damaged area and to the strong back to tie the deck section to and reinforce the strong back. Again there was no damage to the strong back due either to the accident or to cumulative stress to this area.

    The application of glass to both sides of the strong back and to the deck sections forward and aft of the strong back created a very strong integral structure to support the mast.

    The strong back area (both sides and bottom) was reinforced with multiple layers of vinyl ester saturated fabric including unidirectional cloth and x mat.

    The lamination extending from the cabin liner aft of the bulkhead around the strong back to the lower deck laminate in the V Berth area is continuous and seamless. The seam between the remaining Formica and the original gelcoat cabin liner and deck section was sealed with 3M 5200 and topped with a bead of 3M 5200.

    I know that all of the above is counter to the prevailing discussion on this page. My point in adding this post is to indicate to those who may be interested that solutions are available other than the removal of their strong backs or installing often unsightly and always conspicuous steel plates on the bulkhead. The choice is a matter of approach to solving a real or assumed need to strengthen the mast support system. Regardless of what is done to this area, the cored deck section beneath the mast as installed is a vulnerable area for compression. Creating an integral unit (deck, cabin liner, and strongback) in my opinion solves this problem.
    Scott

  15. #60
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    GREAT forensics, Scott.
    Love this kind of attention we give the ole girls.

    Those extra laminations sound like a real good solution to making the whole strongback/bulkhead and mastload area as rigid and immovable as possible.

    Think of you as in the restoration camp of Ariel upgrades. You are careful to honor the original intent of the designer/architect....whot's his name?

    Many owners will want to see photos of your work. I know I'd like to see how the glassing went.
    And the final result!

    [Ebb has his caveats:
    All rain water intrusions from the deck thru the repair area have to be completely sealed, ie bolts, screws, chainplates, electrical holes.
    There should be no standing fresh water possible inside the mast. Don't want any water getting inside the new skin.

    It sounds like you had the beam incorporated into the new interior skin reinforcement.
    If you have an original oak strongback and it is now covered you might get away with it because of its age.
    New oak won't accept regular polyester imco. I haven't worked with epoxy modified polyester.
    But, as you know, if you laminated over everything (ply bulkhead - strongback - overhead) you are now getting the whole area into sharing the support of the mast load.

    For DIYs: Styrene is a dangerous volatile component of vinylester. You ought to wear an appropriate canister mask for interior work and keep the boat clear of heavier-than-air fumes with forced air.
    Imco vinylester should only be used by pros.
    The right epoxy is much more user friendly and does a better job of gluing dissimilar materials together.

    It must have been a difficult job of work - especially the prep and overhead work - and all the corners that had to be turned with wet Xmatt - would like a peek.]
    Last edited by ebb; 05-26-2009 at 09:31 AM.

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