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H16 hatches for ventilation  Bottom

  • I have 2 starboard hulls and one port hull in my collection. The surviving starboard hull from our first H16 weighs 85 lbs. The port hull from the new boat weighs 101 lbs. The starboard hull from the new boat weighs 128 lbs!

    The heavy hull is the one that had the bondo covered hole in the bottom. I'm thinking there must be trapped water. I'd like to add a port for ventilation so I can dry it out. I see curved inspection covers are no longer available. I've read some discussion on this and the Hobie forums regarding adding inspection covers, but would like to get some more feedback. I'm assuming a 5" cover, between the pylons, with some fiberglass build up to make a flat surface.

    I'm thinking I'd do a trial on the 128 lb hull first. See what some heat and airflow would do to the weight.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • Do you see any other places that have been repaired? Backyard boat repair can add some weight. I’m always hesitant to cut into stiff decks, sometimes can offer access to do a repair but I wouldn’t do it just for ventilation.
  • I’m a big believer in ventiation. Fiberglass does not like constant moisture exposure. Not only does moisture add weight, but it will also reduce the strength of the fiberglass. Just popping a drain plug is really not enough airflow to keep the hull dry, especially if there is water pooled in the bottom of the hull. And it is amost impossible to completely drain a Hobie 16 through the drain plugs. An access port in the deck will provide a lot of air circulation. If only adding the port for ventillation, I would just use a 4” port. If you need access inside the hull, then 5”. You can bed the port on a contoured deck using West Six10 epoxy. Mask off the deck around the hole. Scuff up the gelcoat with some 80 grit sandpaper. Then squirt a bunch of Six10 on the flange of the port and push it into the hole. Use a squeegee to clean up the excess and then let it cure. Then drill your mounting holes and fasten with screws.

    All that being said, if you have a Hobie 16 hull that is 20 or 30 lbs overweight, it probably also has a lot to do with manufacturing variations. Older Hobie 16s didn’t have the same manufacturing or quality control processes as the more modern boats and were considerably heavier.

    sm
  • I think I'll try and ventilate the 128 lb hull, and if I like the results I'll put hatches in the other hulls. I've got a couple of 4" hatches on order.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • (Devil's advocate reply....something to consider...)

    Minimum boat weight for the earlier H16s was only 20 pounds more than current production. Even if that was all in the hulls, it's only 10 pounds per hull. The 128 pound hull is approaching double the weight of a new one. It is possible that some of the water weight is in the styrofoam flotation blocks between the pylons. They were originally covered in a plastic film that deteriorates over time. Not uncommon to have plastic bits flow out of drain holes on older H16s. That said, I think it's highly likely that a bunch of water is in the foam core of the hulls, and I'd be surprised if ventilation will make a significant dent. I'd suspect that irreversible damage has occurred in the foam core and, even with a lot of work, the hulls won't be significantly faster or better structurally.

    The mate to your lightest hull has already failed catastrophically, and putting a lot of work into the other three to prolong that a little sounds very iffy to me. The hobiecat.com forums contain many "restoration" threads where extensive repairs, even shiny new paint jobs, were done on crappy hulls that failed shortly thereafter. Perhaps it's time to either spend some cash on decent H16 hulls or put that money and effort toward the SC17. Either way, instead of working them, I'd recommend you just sail the snot out of your existing H16 hulls...nuke 'em 'til they blow!

    Not trying to be ugly...I've enjoyed reading about your adventures and am impressed with your fab/repair abilities. At some point, though, one might need to consider whether one is seeing the beachcat forest for the old H16 tree, or putting lipstick on a pig, or beating a dead horse. (Is it Metaphor Monday?)



    Edited by rattlenhum on Sep 06, 2021 - 10:38 AM.

    --
    Jerome Vaughan
    Hobie 16
    Clinton, Mississippi
    --
  • Jerome,
    Everything you say makes sense. I'm thinking the ventilation will keep the hulls I have sailing longer, not make them any better. I think the 128 lb hull is finished. In the name of science, I'm going to cut a hole in that one, cook it, and see what weight it ends up at. The goal is to keep the H16 sailable and get the SC17 ready this winter.

    I will be on the lookout for better H16 hulls, but remember I'm cheap. No matter how much it costs me!

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • A quick update, with pics to follow. I got my 4" hatches and cut holes in the hulls. There is water in there. Super humid and the inside surfaces were damp. They are in the sun with a leaf blower shooting air in the 100 lb hull. I just found my other leaf blower and will set up both when I can.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • I used my nifty dremel attachment to cut the holes. I practiced on some scrap luann ply to get the setting right.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135613&g2_serialNumber=3

    Hatch slid in:
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135614&g2_serialNumber=3

    I found a major disbond on this hull. I installed the hatch to be centered on it. Here's a video of the disbond. It had been "fixed" with plumber's putty.
    https://youtu.be/ChIBtVZi0H0

    I sanded out the seam.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135615&g2_serialNumber=3

    It was wet inside. I stuck the hull out in the sun and ran the leaf blower in it.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135616&g2_serialNumber=3

    I'm going to make a 3d printed tool to make it easy to get the right flox shape for the hatch. More to come later.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • The seam is bonding. I worked epoxy into the seam, both inside and outside, and clamped the crap out of it.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135620&g2_serialNumber=3

    I'm going to fair that seam inside with some flox, and lay a ply across as well. I think it will be good.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • I went over and pulled off the clamps this evening. Looking good.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • Here is a view inside after a bit of sanding. Hard to get my arm in there, sort of wish I had 5" inspection ports.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135625&g2_serialNumber=3

    You can see the nice epoxy fillet at the joint. I'm pretty happy with this so far. I think I'll fill in the joint a little with some flox and glass it, just to ensure strength. I'm also going to leak test this hull, using the little shop vac and my modified adapter with the holes in it. Plus I'll tape over the inspection port hole, assuming the tape will be weaker than the hull.

    My 85 lb hull lost 0.4 lbs after ventilation. My 101 lb hull gained 6 lbs after ventilation. I suspect a measurement error there. I think the main benefit is dry insides should extend the life of the boat.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • Here I've scraped some of the foam out around the perimeter of the hole. This is so I can fill the space with flox. Will make the hole stronger, plus we want to be able to screw down to it.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135651&g2_serialNumber=3

    I designed and printed some tools to help with the floxing. The two half circle tools are glued down with superglue in a few spots. I made it in two pieces because my printer was not big enough. This will actually make it easier to remove, so it's good for that reason. The circular part with the white electrical tape on it is to hold the flox inside the hole, plus give me a dam to keep the flox from going into the hull.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135652&g2_serialNumber=3

    Here it is all floxed up and curing.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135653&g2_serialNumber=3

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • I went over and did a little sanding, then popped the forms off. There are a couple of voids but overall it looks good.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135673&g2_serialNumber=3

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • On the first hull I tried to get flox in place of the foam core that I removed, and I also tried to cast the top at the same time. Bad idea. Works better to get the flox between the hull glass layers first. The mounting holes were premature here. It's better to make the flox thick enought that it won't run, and inject it into place. After it dries, sand it and move onto the next phase.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135739&g2_serialNumber=3

    Here is the drilling process.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135737&g2_serialNumber=3

    Finished hatch install fairing. Just need to paint and screw it on.
    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=135732&g2_serialNumber=4

    I've got the other hull port mount sanded flat. I made a big sanding block out of plywood so I could make it flat. I just need to sand the extra flox out of the hole so the hatch will go in, drill the holes, then paint the hull.



    Edited by waiex191 on Sep 14, 2021 - 02:30 PM.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • QuoteHere is the drilling process.

    Love the clecos, (sp?).
    Many years ago, I flew floats, in the NWT, turbo Beaver & twin otters.
    Double Otter floats were worth $1/4 million, 40 years ago.
    At the end of the season, after being beat up on the Barren lands all summer, some poor apprentice would be inside the float- “draw”, bbbrrrrpppp, “rivet”, bap bap bap, no more than 6 hits I believe was the approved standard for proper riveting...they had hundreds of clecos to hold complex curves in place.



    Edited by Edchris177 on Sep 15, 2021 - 08:09 AM.

    --
    Hobie 18 Magnum
    Dart 15
    Mystere 6.0XL Sold Was a handful solo
    Nacra 5.7
    Nacra 5.0
    Bombardier Invitation (Now officially DEAD)
    Various other Dock cluttering WaterCrap
    --
  • I've set (and drilled out) a lot of rivets. I've never heard of a maximum number of hits, but they do work harden so you want to whack them hard enough to set them quickly. If you use too small of a gun on a big rivet, it's trouble. You need the right gun for the job.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --
  • When adding a access hatch, I add two support "beam" under the deck made from main sail batten stock. Just cut out a cardboard template that bridges both sides of the hull and matches the contour of the underside of the deck. This batten support needs to be perpendicular the the underside to add strength . Place these supports parallel to each other and about 2" from your cut hole so as not to be in conflict with your fasteners and fiberglass them in place. Now you have made your deck strong again right next to that big hole you cut in your boat .............Placing the hull upside down on a pair off sawhorses allows you to use gravity as your friend when using fiberglass there. And do all of this before fastening your access hatches in place....you will have more room to work and not get fiberglass were it does not belong. icon_wink

    --
    Bill 404 21SE
    --
  • Good idea. I think with the flox between the layers, and even the ring bolted in, that will also be adding structure. I've placed my hatches under the tramp, so they will never be stepped on. I'm assuming the loads there are lower than just in front of the pylons.

    I do worry about how much weight I'm adding. Just like in aviation, weight is the enemy. I plan to weigh the hulls again after this project is complete.

    Someday, when I'm rich and eccentric, I'll make my own molds and make a carbon fiber H16 in my autoclave facility. I'm making good progress towards that goal, 50% to rich and eccentric. I'll leave it to the reader to guess which 50% is already covered.

    --
    Bryan in Poplar Grove, IL
    Supercat 17, unknown year. Future project
    Hobie 16, 1977 - died a spectacular death https://youtu.be/Y7O22bp2MVA
    Hobie 16, 1978 - current boat
    --

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