Sea Chest

Home Forums Other Boat Systems Sea Chest

Tagged: 

This topic contains 27 replies, has 10 voices, and was last updated by  hjhazeltine 6 days, 17 hours ago.

  • Author
    Posts
  • #1507

    admin
    Keymaster

    By Brooke Williams

    Mirage sea chests are low maintenance but definitely not zero maintenance. Bottom growth will accumulate on the intake grill and eventually restrict inflow of water. Therefore, the grill needs periodic cleaning. If one is in clear water, a quick look down the column will tell you when a cleaning is necessary. St. Johns River biologics fouled Cristina Sea’s sea chest to the point that restricted water flow caused engine overheating. Normal underway speeds will draw down the sea chest water column. Combine this draw down with restricted intake and the draw of the engines can suck up all available water.

    Christina Sea’s intake grate was cleared by scraping the inside with a paint scraper and brush cleaning the underside. We have found that attempting to clean the grill from the inside with a brush to be almost totally ineffective. A brush’s bristles will clean a grate’s surface but not do an adequate job of clearing the holes. Moral of the story: do not rely on a diver to keep your sea chest clear while cleaning your bottom.

    A power washer does an excellent job of cleaning from the inside. The nozzle tip needs to be right down on the grate as the surrounding water will instantly decelerate the washer’s spray. This drill is one of the few occasions when one can get aggressive with a power washer on these boats. The bottom outside could still have some growth on it but the intake holes will be totally clear.

    If the boat is in murky water, inside visual inspection is impossible and one may not be able or inclined to inspect the bottom. In that case, an owner can figure out when water is restricted by underway observation or just set a periodic cleaning routine based on water conditions. The underway check is simple and recommended as part of a periodic inspection routine. First, note the surface level of the water column when the boat is not running. Then note how much it draws down when underway at normal cruising speeds. It would also be useful to check the column when experiencing differing sea conditions. We have found that running does draw down the water column a bit and that once very heavy following seas drew down the water column enough that restriction of flow would have caused a problem.

    Expect to need to clean the intake grate a couple times a year depending upon water conditions. This year’s East Coast drought has made conditions particularly conducive to bottom fouling. Moon Beam had propeller barnacles grow so fast after a propeller cleaning that three weeks later it could turn no more than 2,000 rpm. Others have similar stories. If the grate is getting fouled probably the rest of the bottom is as well. Thus, the final recommendation is to dive on the bottom regularly whenever possible.

  • #8422

    Chuck Truthan
    Participant

    We’ve had our sea chest for 2 years and have not had to do any additional cleaning other than the standard power wash when the boat is hauled (which has been annually for us).

  • #8430

    Norm Miller
    Participant

    We have had Quiet Company’s bottom painted twice and that has been the only times we have touched the screen on the seachest. It a great location for a raw water temp Sensor.

  • #8593

    James Wascko
    Participant

    How drastically will staying on the hook or ball for long periods of time vs cruising regularly affect the sea chest?

    I ask because right now just getting a secluded anchorage and not moving for a month sounds Soooooooo good. 🙂

    Thank You
    Jim

  • #8594

    You will be running the generator and circulating water regularly while staying put, so I don’t think you’ll notice any difference. Personally, I would continue with my weekly visual inspection / brush cleaning routine whether I am staying put or moving.

    Dick
    Avocet, N37-08

  • #8595

    James Wascko
    Participant

    Thank You Sir!
    That sounds Great.
    Jim Future N Owner

  • #8596

    Joe Pica
    Participant

    Jim,
    Depends,
    Where(fresh vrs salt, cold vrs warm), static vrs. moving water, how long and whether or not you will be on board need raw water e.g. A/C units or water maker. If raw water intake not needed just plug(overkill for a month)
    (keeps growth out) the inlets of the sea cocks close the seacocks. Now when the bottom is cleaned clean the grate. Some have rigged a strainer basket in lieu of the fixed grate. that can be removed and clean form in the boat … Office ll I think Cedric Walker.

  • #8597

    Norm Miller
    Participant

    Ken Fickett told us to just use a power washer from inside to spray off the bottom screen. We have a Karcher electric power washer that does a great job. It has a spray wand that is able to reach the bottom of the sea chest. We have never had to do it even after winter layover. We are on the Ohio river.

    Norm

  • #8598

    James Wascko
    Participant

    Thank You Gentlemen
    All of your answers are very pleasing to me. It’s awesome getting real experience information that you can trust.

    As Joe was talking about all the different types of water and situations it hit home. That was some of what I was concerned with.

    As Dick and Norm talked about the pressure washer and regular checking was indeed what I was hoping to hear or learn.

    The thought of having to have a vessel hauled out every couple of weeks for cleaning, well didn’t please me at all.

    For me, well I would probably be more to the extreme and check and or clean daily.
    The Sea Chest in the Great Harbours has always been an important factor in researching trawlers.

    Thank You again Everyone
    Have a safe and wonderful 2017
    Jim

  • #8602

    cedric
    Participant

    As Joe Pica mentioned, I added a screen that can be removed for cleaning from inside the boat. It’s just some stainless bar stock and a piece of perforated ABS. Andy Allen, the prior owner, had trouble with with marine growth covering the fixed-in-place screen and so he had it removed. Then I aspirated a bunch of acorns out of the waterway, into the sea chest, and thence into the Groco stainer inlet hoses. It made me realize the wisdom of a screen at the bottom of the sea chest. If anyone wants to see photos of my removable strainer send me an e-mail cfw (at) tulane.edu and I’ll take some next time I pull it for cleaning.

    • #8659

      Steve Ehrler
      Participant

      Cedric –
      Would love to see some pictures of your sea chest screens! It appears that we just ran into a situation where the sea chest grate was partially clogged. The starboard engine (highest sea cock on the sea chest) was starved for water and things started over heating. We tried cleaning with a power washer from inside but either lack of proper technique or not having a fine enough spray prevented us from cleaning it adequately.

  • #8661

    Chuck Truthan
    Participant

    Cedric –
    please post pictures on the forum!
    Chuck Truthan

  • #8662

    James Wascko
    Participant

    I would be very interested in seeing these pictures too.
    Thank You
    Jim

  • #8669

    Norm Miller
    Participant

    Steve and Jim here is the picture you are looking for:
    https://drive.google.com/open?id=0B3GY-ZUCLmydSlNJRnRMZ2hTOTQ

    Let me know if you cannot see it.

    Thx
    Norm

    • #8680

      James Wascko
      Participant

      Thank You Norm,
      I like the simplicity of it.
      Easy to maintain and to manufacture
      Jim

      • This reply was modified 1 week, 3 days ago by  James Wascko.
  • #8672

    Chuck Truthan
    Participant

    Why the center cross piece and what appears to be a hinge joint just above that? Not enough vertical clearance to remove it straight up and out?

  • #8674

    cedric
    Participant

    Try this link for a series of photos showing the operation of the screen. When folded you can insert it from the top of the sea chest. As the screen goes downward you straighten the hinge which is stays stiff with a couple of nylock nuts. Hope these help.

    https://www.dropbox.com/sh/ayfyhu2g40uu399/AACPEASrQmpxZNxUP1B7l6-Sa?dl=0

    Attachments:
    You must be logged in to view attached files.
    • #8682

      James Wascko
      Participant

      Thank you cedric for the series of shots.
      I like it.
      Jim

  • #8676

    Chuck Truthan
    Participant

    Thanks for the series shots!

  • #8683

    Bob Miller
    Participant

    If someone would put together a kit for the parts to make one of these removable screens I would be first in line to buy one. If not, I would like to know where I can buy the materials.

    • #8684

      James Wascko
      Participant

      Bob,
      I would inmagine just about any good hardware or home improvement store would have everything.

      I would at least stick with Stainless or Brass nuts and bolts and washers.

      Looks pretty easy to make and maintain and that’s Always a Good Thing.
      Have a great day!
      Jim

  • #8685

    Bob Miller
    Participant

    I don’t think I have seen that perforated thick material that the actual screen is made of.

  • #8686

    Bob Miller
    Participant

    Perforated ABS looks about 1/4″ thick.

  • #8687

    Joe Pica
    Participant

    Bob you will need to remove or have removed the existing screen screwed flush to the bottom of the boat. It is perforated stainless steel held flush against the hull by four ss screws. The screen nests flush with the hull in a very slightly routed out 1/16″ lip. This makes the screen completely flush. I suggest just to use that ss screen in lieu sourcing the plastic which if desired can easily be drilled. If not happy with the ss screen switch to abs plastic. The entire strainer is easily made with simple tools and big box material. The only issue is getting(sizing) the screen to pass the sea cock mushroom heads that protrude slightly into the sea chest tube without creating too large of a gap. You could probably add a perforated flexible seal(same stuff on exhaust flaps(?) that would prevent an excessive gap.

  • #8688

    Bob Miller
    Participant

    Thanks Joe.

  • #8691

    Steve Ehrler
    Participant

    Thanks for all the pictures and the explanation ! Love the simplicity. Seems like removing the screen and cleaning it would be much easier than trying & hoping a pressure washer does the job.

  • #8729

    hjhazeltine
    Participant

    On Blues Skies GH37 Hull #3, I purchased the box of the sea chest from Mirage. Installed it at Renovator Yacht with a removable GRP grate.

  • #8730

    hjhazeltine
    Participant

    In the summer in St. Pete, If I clean the sea chest every two weeks its an easy job. If I wait a month it is miserable.

You must be logged in to reply to this topic.