Polyester resin hull restoration

Discussion in 'Materials' started by Mmcco, Jan 24, 2017.

  1. Mmcco
    Joined: Jan 2017
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    Mmcco Junior Member

    Hi, new here.

    Just bought a little Hunter 25 as a project boat, looking to convert it to be a tiny live aboard with all the solar power you could need and to run on and electric motor!

    But first I have a widespread osmosis issue to take care off.

    The Osmosis is not that deep from first investigation and is only just under the gel coat, I was going to give it a deeper sanding and re laminate some glass with epoxy which would sort my issue and be good with a quick fix for the next 10 years. Am I correct in thinking that?

    I have had a second thought as my boat is a polyester hull and it's not ideal for heavy or blue water sailing and it was origanly built in 1983. If i ground the osmosis out and used carbon and epoxy and then went on to put a layer of carbon laminate on the whole outer hull would I need to do the same in side as it would leave me with an uneven laminate sandwich? Could this cause more problems in the long run? If I did the inner and outer hulls would I then need to look at doing something with the deck to keep the boat at a constant stiffness?

    Any help, opinions and suggestions welcome.
     
  2. gonzo
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    gonzo Senior Member

    For osmosis repair, it is not necessary to laminate with fiberglass or any other fiber. There are many epoxy barrier coats that work fine. Simply adding a layer of carbon fiber is not going to convert the boat to a blue water cruiser. The rig, deck hardware, rudder, etc. are not design for heavy weather either.
     
  3. upchurchmr
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    upchurchmr Senior Member

  4. PAR
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    PAR Yacht Designer/Builder

    Osmosis and blister repairs are pretty common with acceptable practices. Making them harder to do for dubious value, doesn't seem reasonable.

    Decide what you want, then establish a plan of action. If you want a blue water cruiser, the Hunter 25 will get you most of the way there, though some expense will be necessary upgrading it to a suitable level, which has little to do with the hull shell. For example, a new inventory of heavier weight sails, plus trisail, heftier rigging both standing and running, self steering gear, heftier ground tackle with a lot more rode/chain, navigation equipment and other electronics, improved propulsion, larger tankage (fuel, drinking water, gray and black, etc.) and it's associated plumbing and monitoring, all would need to be addressed, having little to do with the hull shell.

    Pricing out the carbon as you've envisioned, should put reality into your proposed plans for its implementation.
     
  5. Mmcco
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    Mmcco Junior Member

    In I am aware I,ll need to do a bit more that that, the main reason for a carbon skin is that polyester hulls are **** just by the nature of the product, they are not strong and would not recommend anyone with a poly hull to head out in to the big blue or a perticularly rough sea.

    Ans suggestion on the lamination question?
     
  6. Mmcco
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    Mmcco Junior Member

    Hi, thanks for the links I'll give them a read, the reason for the carbon is strength, the boat is a 35 yr old polyester resin hull, they are just not that strong (polyester means meany polymers and it reacts with everything). I know I could just faire the hull with epoxy but if it's out the water it's only another weeks work. But will the uneven laminate sandwich cause issues down the line?
     
  7. Mmcco
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    Mmcco Junior Member

    Hi, thanks for they replays, but I am aware of all the additional things I need to do make a boat a blue water boat! I am looking for answers to the uneven lamination questions if put a skin on the outside of the hull.

    Regards
     
  8. PAR
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    PAR Yacht Designer/Builder

    You ideas about polyester hulls being non-blue water capable, is simply flying in the face of reality and the existing millions (literally) of polyester boats, that have or will plow blue water away from their bows.

    Again, blister repair is pretty basic and not particularly difficult work. Your boat, like many of that era have experienced them, techniques and materials have been developed to address them and it's well established. Even the worst blister job can be handled, though yacht value often comes to play, most blister jobs are an inconvenience, but manageable. Maybe you can post some pictures.

    Your understanding of polyester might be flawed, as epoxy also means polymers. About the "uneven laminate sandwich" well, I think you're attempting to "balance" the laminate, by putting carbon on both sides of the polyester hull shell. In a technical sense, you're correct, you should aim to have a balanced laminate, but if polyester is the core of this sandwich, you're not gaining much, in terms of strength, unless you pile on a lot of carbon and you're also gaining weight, defeating the reason for employing carbon in the first place.

    I once took a racer, which had a serious blister issue and peeled about 1/2 to 2/3's the polyester laminate off the boat. Some of this was to remove the gelcoat and start over, but most of this was done on the inside of the hull shell, after the deck cap and liners had been removed. The resulting, quite flimsy hull shell, was then given about the same amount of carbon (thickness), as the previous polyester laminate, but only on the inside. Repairs were performed on the outside and it was re-gel coated. The finished project was considerably lighter and stronger, but a huge job. Because it was a racer, the costs could be justified to keep this competitive yacht in service, but on a cruiser, hardly quantifiable.

    Again, a blue water boat is about hull integrity and the Hunter 25 just barely qualifies, but in capable hands a fine boat. This is the point. If you want a blue water boat, you should consider a larger vessel, one intentionally designed as a blue water craft. This said, you could make this Cat. B yacht, into a Cat. A, but adding layers of carbon wouldn't be the route most would take, nor necessary, compaired to having it equipped properly for blue water work. In other words, you can take this Hunter pretty much any place you'd like, if well managed and equipped. On the other side of this coin, you could enbaum the boat in carbon and find yourself in a world of hurt anyway, just off a lee shore after making a hasty decision or other simple skippering mistake. My point, a blue water boat is yes, a reasonable hull choice, with appropriate equipment, but more than anything, it's about the skipper and crew's abilities. Ask yourself how much of small boat, blue water sailing experence you have and if you'd like to learn it on a small boat. Finding yourself in 30' rollers in a 25' boat can be terrifying and is dangerous, if you don't know what to do. 30' rollers in blue water isn't an unusual thing.
     
  9. ondarvr
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    ondarvr Senior Member

    Interesting thought, but not accurate.

    When building a hull you build it to handle certain loads and stresses, both epoxy and polyester/VE can be built to take similar loads, the difference is in the weight, a polyester build will typically be heavier.

    In some applications weight is critical, so epoxy is the easy choice, in others cost is a bigger factor so polyester is used.

    The design and build of your hull is the limiting factor, not the resin type.

    Due to the cost and hassle of adding layers of carbon to the outside and possibly the inside of the hull, you would be much better off financially to sell what you have and buy what you want.

    There are very good guidelines in print on how to repair a blistered hull, so you can choose how thorough you want to be in removing them and preventing their return.
     
  10. Scot McPherson
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    Scot McPherson Senior Member

    With very much respect, I am not sure the hunter 25 is really a good choice for a small blue water hull. Hunter 25s typically have fin keels with a spade rudder which is great for racing in mostly protected waters. In conditions where you can find yourself on top of a wave, a full keel is desirable.

    A fin keel with a spade rudder well separated from the keel has a much greater tendency to spin while atop a wave, which means a higher broaching potential which is perhaps the worse possible thing that can happen second only to a turtle capsize.

    A full keel has a longer keel with the rudder butted against the after end of the keel, and it helps resist spinning atop a wave. Additionally because full keels general dig with less depth into the water, they roll a bit more gently and don't get smacked around as much.

    Carl Alberg designs make good blue water boats, the seasprite 23 or 30 are fantastic boats in large rolling waves, however as PAR indicated, it requires a skipper that knows how to handle a boat in heavy seas.

    Hunter 25s are known to make great boats for short blue water passages such as Florida to the Bahamas with proper planning which means beyond outfitting and supplies, knowing ahead of time what conditions they are going to experience and not going or turning back if conditions are really too much and unsafe. Lots of people make this passage in hunter 25s every year.

    I'd pick a larger boat, like a seaprite 30 or alberg 35. You can usually pick them up for pennies on the dollar.

    Check out the movie "Jean de Sud", it's downloadable and streamable. He sailed that boat around the world in an Alberg 30, and he was dismasted, but he was a good skipper and knew what to do and got himself to shore safely to make repairs.
     
  11. PAR
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    PAR Yacht Designer/Builder

    I disagree in that fin keelers are bad sea boats. Statistically, the vast majority of blue water boats are fin keelers. Scot, you're letting you age show, we're long past the long/fin keel debate, by a half a century I'd guess, though arguments can be made for and against, not really justifiable or quantifiable in a true sense.

    The Hunter 25 is at the low end of the spectrum for a deep water boat, but it can be employed. Again, it's more about skipper and crew skills and reactions, than anything else when well offshore, as I'm sure you know. Hell, a Flica can be considered a blue water boat at 20', but you wouldn't catch me making the San Diego to Maui run in one of these puppies, full length keel or not.
     
  12. Scot McPherson
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    Scot McPherson Senior Member

    Hey Paul,
    Not to be argumentative, but travel by automobile is one of the unsafest forms of travel, yet more people travel by car than by any other mode of transportation.

    The usage statistics don't tell you anything except that more boats are made this way than that way. Most people buy what the dealer sells them. We've discussed that inadnauseum on this form as well I think.

    Your thoughts?
     
  13. Mmcco
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    Mmcco Junior Member

    Lol! We have gone of topic some what,

    ignore the blue water aspect on my post I like in Scotland a nice day sail is 20/30knots and anything from 5-15 foot seas! Your boat needs to be robust regardless what you plan to do with it!

    My boat needs to have the osmosis addressed, I have a friend who has a company making carbon fiber car panels so the cost is not an issue,

    I would rather Cloak the whole outer hull to stop any water ingress going forward in as carbon epoxy is good barrier for this.

    I just need to know that if I do the outer hull will I need to the inner to balance the laminate (thanks for the correct terminology PAR) or will doing the outer hull only cause no issues with structure in future years.

    And the epoxy polyester debate! What I meant to con any PAR, was that epoxy is made from the same groupe of polymers where as polyester is made from polymers from lots of different groups (petroleum, acids, alcohol and Coal to name a few) which are all highly volitile chemicals in there own right, even once cured these different groups can still react with each other given the correct catalyst and you have control over what's in the water your anchored.

    And ondervr epoxy is a much superior product to polyester stench in most failure aspects its 20/30% weaker tha epoxy and is nowhere near as stable a compound.
     
  14. Mmcco
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    Mmcco Junior Member

    That's a fair point but but you'll find historically more boats have been made from wood but the bad ones are bio degradable, not for sale on Craig's list to people who don't know what they are buying!
     

  15. upchurchmr
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    upchurchmr Senior Member

    Carbon fiber is not better or worse for water ingress. Its the resin that matters.
    Epoxy is best.

    No one can guarantee that a single layer of carbon will or won't cause a structure problem without doing a design study.
     
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