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Where to install hull ports?
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=9946		 Page 1 of 1
Author:  lewisa97 [ Sat Jul 05, 2008 10:32 pm ]
Post subject:  Where to install hull ports?
I have a delamination problem with my 83 Hobie 16. The soft spot is on the deck in front of the forward post. Would it be acceptable to install a hull port in this area? I would appreciate any opinions on this.
Thanks
Author:  drej [ Sun Jul 06, 2008 6:15 am ]
Post subject: 
That is a traditional area to install hull ports. Some may disagree, but I would ensure I have fixed the delamination issue first before I installed the ports. That will ensure you have good penetration to all areas of the delaminated areas. (the process involves drilling holes partway through the deck and then forcing epoxy through all the delaminated spaces).

If you do install the ports afterwards), remember to take epoxy and coat the freshly cut area to keep moisture from getting in there

You can find tips and instructions under the Help with Repairs category.
Author:  waldorf [ Sun Jul 06, 2008 8:58 am ]
Post subject: 
this article may help you decide......
http://www.thebeachcats.com/Article29.html
Author:  J_Eaton [ Sun Jul 06, 2008 7:10 pm ]
Post subject: 
Why do you need a port? A port only weakens the structural integrity of the deck. If the delam is area is not too big, fix it and sail the boat.
Keep the bows up when storing, if possible, and ALWAYS drain the water out after sailing :)
Author:  drej [ Sun Jul 06, 2008 7:59 pm ]
Post subject: 
Can't argue with that logic - but done well, a hull with a port in it will last a long time. My old 84 is still rock solid with ports in both hulls.

I guess the only thing it would do, depending upon how big the delaminated area is give you an excuse to cut out some of the repaired area

Either way...fix the delaminated portion first...then figure out what you want to do with the port
Author:  Banzilla [ Mon Jul 07, 2008 6:41 am ]
Post subject: 
If you have to have ports for some reason. would it not be better to put the ports in the stern or between the pylons?

Sam
Author:  lewisa97 [ Mon Jul 07, 2008 12:53 pm ]
Post subject:  Thanks for the great advice.
I think I'll fix the delamination first, then decide if I really want to put a hole in my boat.
Author:  J_Eaton [ Mon Jul 07, 2008 12:55 pm ]
Post subject:  Re: Thanks for the great advice.
lewisa97 wrote:
I think I'll fix the delamination first, then decide if I really want to put a hole in my boat.
:wink: just because everyone else jumps off the cliff, doesn't mean we have to
Author:  speed633 [ Mon Jul 07, 2008 8:32 pm ]
Post subject: 
i have a 1978/80 hobie 16 and am planning on installing port holes so i can access the pylon shoes, which have broken loose as demonstrated by the large crack in the hull. given the similar vintage of your boat i'd recommend checking for similar cracking (look below the front pylon mount) if you find any evidence of cracking here, you have plenty of reason to install the ports. as far as placing the port between the hulls, make sure you do it behind the shroud, as there is a lot of stress between the shroud and the forward pylon
Author:  J_Eaton [ Mon Jul 07, 2008 8:42 pm ]
Post subject: 
Quote:
as there is a lot of stress between the shroud and the forward pylon
please, I'd like to hear/learn/understand more about the stress on the deck in this area
Author:  cookwithgas [ Tue Jul 08, 2008 11:02 am ]
Post subject: 
DON'T DO IT! I just cut up my "old yeller" hulls that had ports. With use, the port holes will flex and crack your covers. Keep the hulls in tact and do the epoxy injection to repair the tops. I did this with an old set of blue hulls and they are SO much better than the yellow ones with the ports. The ports will look good when you install them, then the covers will start to crack and you will get water .

Just say "No" to hull ports. I posted some pictures here of my "old yeller" hulls and my blue hulls:

http://www.cooknwithgas.com/Sailing/Hobie_Repair.html

The blue hulls have been out four times this summer and they don't leak like the ported, yellow hulls.

Scott Laughlin
Omaha, Nebraska
Author:  aschaffter [ Tue Jul 08, 2008 3:36 pm ]
Post subject: 
I think the ports fail because the deck in that area continues to flex.

From an engineering standpoint, ports weaken your hull. Fiberglass Hobies hulls are constructed with a fiberglass-foam-fiberglass sandwich, which in engineering is a structural beam- the foam is called the web and serves to keep the skins apart- the same principle as in airplane wings- two skins held apart by ribs. A port removes skins in an area and replaces them with a weaker single skin (plastic port) and so creates a weaker and more flexible area.

Now if you want to add ports to a delaminated hull and end up with something that is actually stronger but not much heavier than the original, here is what I would do.

    1. First locate, size, and cut the port openings.
    2. Carefully remove 1 1/2" more of the inner fiberglass skin from around the hole on the underside of the deck. A Dremel-like tool with small circular blade works well. It is ok to cut into the foam, but do not cut into the outer skin.
    3. Use sandpaper to transition the foam back so it is totally removed from the first 3/4" of the backside of the outer skin from the edge of the hole then slope it to the inner skin. Roughen and clean the 3/4" of exposed outer skin
    4. Next join the inner skin to the outer skin by laminating 3 or more layers of glass to the underside of the deck starting at the holes and going outward across the tapered foam, and up on to the inner skin a couple of inches past the delaminated areas. Make sure you roughen and clean the old glassed area first. It may be easier to make a hole in the glass fabric that is slightly larger than your hand then wetting out the glass and doing the lamination on a sheet of plastic wrap- it is easier to apply and squeegy off excess resin that way. After wetting the inside/underside of the deck lightly with resin you can cut a hole in the plastic wrap, put the complete lamination in place on the bottom side of the deck, brush/stipple or roll it down, then remove the plastic wrap. Don't worry if the glass extends into the hole opening, it can be trimmed later. (hull will need to be upside down.) (If the deck were flat a plywood or micarta stiffener could be used under the outer skin)
    5. Make templates that mirror the cross hull profile of the underside of the deck just forward and aft of the holes (outside the tapered area)
    6. Make four (two for each port) 2" - 3" wide deck beams from 1/4" - 3/8" marine ply or rigid foam. Round the edges of the beam that will be away from the deck so you can wrap and laminate multiple layers of glass on it - lay glass fiber on the bias (diagonally to) the edges.
    7. Put "peel ply"* on both sides of the laminated beams (*after the resin has cured and peel ply is peeled off it leaves a rough surface ready for further glassing or attachment) or once the beams have cured roughen the layup on the beam faces with sandpaper.
    8. Re-check and adjust the fit of the beams if necessary to make sure they still match the underside of the deck.
    9. Combine fiberfill and resin to a THICK, peanut butter consistency and bed the beams in it to the underside of the deck
    10. Use extra filler to make a nice transition radius between the beam and the under side of the deck, then laminate a couple of layers of glass (on the bias) to attach the beams to the underside of the deck.
    11. Once everything has cured and the inner skin is rigid and reinforced you can repair the delamination by drilling holes in the outer skin and injecting resin as describe elsewhere here. When that is done, install the ports. You will have a deck that is stronger than the original.


These techniques are used building fiberglass composite aircraft and result in a VERY strong structure.

If you want any more detail about these techniques search composite aircraft building or the Experimental Aircraft Association.
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