Thru Hull Modification

Discussion in 'Catalina 30' started by Jac123, Apr 19, 2019. Add this thread to a FAQ

  1. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    I have purchased new thru hulls and seacocks for my Catalina 30.
    The new thru Hulls are smaller (both in diameter and width to the originals).
    Thought I had it worked out with distributor but miscommunication resulted in this situation.
    Diameter difference old 2-3/8" new 1-1/2"
    Width difference old 3/8" new 1/4"

    Any suggestions on best way to fill in area around and secure new thru hull.
    Thru 1.jpeg Thru 2.jpeg
     


  2. Tom J

    Tom J

    Joined Sep 30, 2008
    1,414 posts, 309 likes
    Catalina 310
    US Quincy, MA
    I don't know, Jac, that's a big difference in size and water flow. You would have to fill in the existing holes and re drill new holes. I think I would put those new valves on E-bay and get the correct sizes.
     


    TimMarks likes this.
  3. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    Yea, I thought it would be a simple replacement.
    I wanted to use composite seacock with a flange but it seems like you can't buy them with the original size thru hull.
     


  4. Ward H

    Ward H

    Joined Nov 7, 2011
    2,273 posts, 497 likes
    Catalina 30 Mk II
    US Barnegat, NJ
    Welcome to the forum @Jac123 !
    This is a good place to ask your question. If there's a solution, somebody here will have it.
     


  5. The Shadow Knows

    The Shadow Knows

    Joined Jun 10, 2017
    148 posts, 59 likes
    Catalina 1980 Catalina 30 Mk II
    US South Pasadena / Tampa Bay
    JA,
    I agree with Tom. I don't know who you got these from so, give Catalina a call in Largo Florida
    @ 727.544.6681

    They should have what you need. Also please do not use gate valves. Look into Delrin ball valves. They will not freeze or have stem leakage & are NOT subject to electrolysis.
     


    Jac123 likes this.
  6. Capt jgw

    Capt jgw

    Joined Feb 8, 2014
    1,034 posts, 72 likes
    Columbia 36
    US Muskegon
    Making the holes bigger is of course easy, but smaller not so much. Essentially you'll have to close up the new holes as if you were eliminating an unused through hull. Should be lots of threads here and other forums on how to do that. It's a big job. Sounds like a good opportunity to reevaluate the placement and number of holes you have. Less is always better.
     


  7. Ward H

    Ward H

    Joined Nov 7, 2011
    2,273 posts, 497 likes
    Catalina 30 Mk II
    US Barnegat, NJ


  8. BigEasy

    BigEasy

    Joined Jun 21, 2004
    1,142 posts, 297 likes
    Beneteau 343
    US Slidell, LA
    Try to return them and get correct sizes. Might lose a few days to get new ones, but save lots of grief trying to retrofit.
     


  9. Harlan

    Harlan

    Joined Jun 4, 2004
    90 posts, 11 likes
    Oday 34
    US Niantic
    Hmmm... what am I missing here? Looks like same size thru hull to me. It is an entirely different STYLE with a different size and design outer flange. Diameter of the threaded portion and inside diameter (water flow) look the same to me. Either glass over the recess for the outer flange and refit or return and ask for the same STYLE. A bigger size will result in a bigger hole thru the hull, different tailpiece being needed, changing hose, etc. etc.
     


  10. jssailem

    jssailem

    Joined Oct 22, 2014
    9,006 posts, 3,921 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    And you may find that the space of the interior compartment may not work for the new sized backing plate and valve. Check both sides of the hole.
     


    Jac123 likes this.
  11. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    Your correct- Same size thru hull but as I was later informed does not come with the original size skin. Hard to believe that no after market composite seacock with flange or collar matched with the original size skin exist.
    It seems like there must of been hundreds of boats built with flush skins and just valves on thru hulls produced.
    Thanks for your feedback.
     


  12. Tom J

    Tom J

    Joined Sep 30, 2008
    1,414 posts, 309 likes
    Catalina 310
    US Quincy, MA
    Sorry, Jac, I'm confused. I thought in your OP, you said the new thru hulls were smaller. If they are in fact the same size, then what I suggested does not apply.
     


    Jac123 likes this.
  13. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    Yes, I didn't state it clearly. It's the skins outside dimensions that are smaller - the opening is the same. So far in composite I can find a skin that matches the original but not a seacock (only a valve) that threads to it.
    The Bronze Groco skin is close - about 1/2" smaller in diameter. If I use 5200 can I bead a 1/4" around the skin to "fair" it into the hull ?
     


  14. Tom J

    Tom J

    Joined Sep 30, 2008
    1,414 posts, 309 likes
    Catalina 310
    US Quincy, MA
    I wouldn't use the 5200 on the thru hull, it will never come off again. A better sealant for the thru hull itself might be 4200. For the outside flange, maybe build up the area of the hull with an epoxy fairing material and then shape it to get close to the dimensions of the flange.
     


    Last edited: Apr 21, 2019
    Jac123 likes this.
  15. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    I think I'm going to give Tom J's method a shot. I was thinking of buying a sacrificial thru hull and setting it in place. Covering the threads with tape and then the tape with some sort of release agent. Applying epoxy around it and when cured removing the sacrificial and installing the new thru hull with 4200. Any thoughts on hull prep, release agent, epoxy, how to keep epoxy in place would be appreciated
     


  16. Ward H

    Ward H

    Joined Nov 7, 2011
    2,273 posts, 497 likes
    Catalina 30 Mk II
    US Barnegat, NJ
    @Jac123 ,
    I know I said I was going to use 5200 for my thru hull install but I changed my mine and went with Siki Flex 291. It's what Maine Sail used in his www.marinehowto.com article on installing thru hulls. Not quite as aggressive as 5200.

    I question the thread compatibility of the Groco bronze thru hulls. According to this excerpt from the Forespar Marelon catalog they use a different thread on the Series 93 thru hull/seacock. Here is a screen shot from their catalog about the threads:

    Forespar Marelon Threads.jpg

    Their "Series 93 Threaded Valves" use the marine standard straight thread, one of the reasons I chose to use that valve. The thread type matches their CF250 thru hull, which matches the ones I took out of the boat.

    I installed my new thru hulls and valves on Sunday.
    Series 93 Threaded Valves.jpeg

    BTW, the shape of the hull at the intake thru hull opening may make it tough to fit the flanged thru hull flat to the hull. My 3" backing plate had to be trimmed due to the curve of the hull.


    Attached is the Marelon catalog.

    Maybe @FastOlson will see this thread and compare what you have to what Marelon valve he used.
     

    Attached Files:



  17. FastOlson

    FastOlson

    Joined Apr 8, 2010
    1,083 posts, 152 likes
    Ericson Yachts Olson 34
    US Portland OR


    Last edited: Apr 23, 2019
  18. Ward H

    Ward H

    Joined Nov 7, 2011
    2,273 posts, 497 likes
    Catalina 30 Mk II
    US Barnegat, NJ
    @FastOlson
    Did the OD of the flange lip on your thru hull look the same size compared to the old white one in the photos @Jac123 posted?
     


  19. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    Yes, thats what I'm thinking about filling in with the epoxy to match the skin of the 93 thru hull. Have not worked with epoxy and am wondering
    if it will "slump" before curing? Also if it will adhere to the hull as well as 5200 would?
     


    Tom J likes this.
  20. Jac123

    Jac123

    Joined Apr 19, 2019
    20 posts, 3 likes
    Catalina 30
    Proud Mary US Forked River
    Oops sorry Ward I jumped in on that :)
     




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