Cutting the deck what will go wrong

[Jackssailboat]

Ok here is a bit of a odd question. I have always loved butterfly vents on sailboats so I made one for my Morgan 33 Outisland. Looks great! Now all I have to do is cut thru the deck, attach and enjoy. However, at this point I'm realizing the idea of cutting a hole in my baby is a dubious idea. So from the collective wisdom here can I cut a hole for the vent without disturbing the intgeitry of the boat. I can cut between the stingers, remove material and finish with epoxy and wood trim. Is this a crazy idea?

[Discovery 15797]

Where are you going to mount it? It looks like you would have to mount this forward of your mast and behind the molded forward hatch and between 2 bulkheads, which (IMHO) would look rather strange aesthetically, eliminates foredeck space, it seems that it will be positioned over the head rather than over the main salon. Or possibly, you are mounting it beside the companionway (which again IMHO would look strange off center). Am I missing something?

Cutting a hole in your deck that size is not a trivial task, and is highly dependent on your fiberglassing skills. You likely have a balsa cored deck. The important thing would be to remove about an inch or so of the balsa where you cut out, and fill with fiber reinforced epoxy putty to seal the cutout. That will also give you a solid foundation for mounting the vent without compressing the deck skins. Then wood trim on the interior.

The short answer is yes it is possible, the better answer is it is highly unadvisable.

[roverhi]

Make sure there is nothing under or above where you want to make hole. If there are trim rings involved, any machinery, bulkheads or whatever be sure they have the space needed. Neatest cut will be using a hole saw if the hole is circular. The cut will expose the core if there is one. Thoroughly coat the exposed core with epoxy resin to seal it from moisture. You could cut back the core and fill with thickened epoxy but a lot of work that probably is not needed. There should be little if any compression issues with a vent, you just need to seal out moisture. A windlass or other high load hardware is another story.

[JPA Cate]

Butterfly hatches are notorious for introducing leaks. I'd say sell it on, rather than introduce a giant hole in an otherwise water-tight boat. I'm sorry if that sounds cold hearted, but your boat is not the right boat for that hatch because it is a modern grp construction. It would be an aesthetic mis-match. ...And of course, there is the question of what that large hole will do to the structural integrity of the boat. Your deck integrity is part of what keeps the hull from flexing too much. The hull and deck together take many different loads.

If your vent is somewhere aft of the boom and ahead of the mainsheet traveler, and you are determined to go ahead with the project, then do not cut straight to the deck beams. Leave yourself about a 2" border. If there is foam or balsa between layers, you'll need to remove that -- if dry, about 1/2" would be enough-- and epoxy with microballoons, so it's firm when it sets, and then install your hatch. Then, if it were me, I'd build a hatch dam around it to protect it from the green waves. [Our hatches have them, and it really reduces the force of the water hitting the hatch.]

Ann

[Jim Cate]

How big is the "vent"? Most butterfly vents are pretty big relative to the boat size, so this is kinda important. And as posted above, just where do you propose to site it?

Beyond structural weakening, you need to be sure that there are no electrical conduits or other unseen structural components running through the cutout area .

Honestly, it seems a risky idea to me... and butterfly hatches are notorious for leaking!

Jim

[Jackssailboat]

Thanks guys for the responses! In the back of my mind I knew this was not a great idea so thanks for talking me down. I have put the saws back in their locker and slowly backed away. For now I will have a completely ornamental non operating decorative butterfly vent. Still ...it does look great. I will post a picture next time I'm down on the boat
Thanks
Jack

[Cadence]

Originally Posted by Jackssailboat

Ok here is a bit of a odd question. I have always loved butterfly vents on sailboats so I made one for my Morgan 33 Outisland. Looks great! Now all I have to do is cut thru the deck, attach and enjoy. However, at this point I'm realizing the idea of cutting a hole in my baby is a dubious idea. So from the collective wisdom here can I cut a hole for the vent without disturbing the intgeitry of the boat. I can cut between the stingers, remove material and finish with epoxy and wood trim. Is this a crazy idea?

Have at it. Make sure your framing isn't flimsy.

[Hudson Force]

Welcome to the forum, Jack. I've lived aboard and cruised Morgan Out Islands for 45 years with 13 of those aboard a 33' like yours. I do agree with those above who advise against introducing new large holes or even small holes in your balsa cored deck. One of the weaknesses with the deck comes with the introduction of water leaks which can spread by absorbing some distance through the balsa and cause soft spots that need repair. I replaced numerous section of balsa cored deck with new balsa tiles, but with each piece separated by a perimeter of epoxy so no water intrusion could spread in the future. In addition, any fasteners mounted to the deck should be placed into areas where the balsa has been removed and filled with epoxy or composite materials.

I would also want to advise you that the deck of your 33 Morgan is more of a cosmetic and functional cover for the contents of your boat than a structural component. Consider the shrouds and fore & aft stays are all mounted to chain plates and fitting directly to the hull and none of them to the deck or any of the lightly tabbed in bulkheads. The mast is stepped upon the keel and the hull from the bilge to sheer line is unusually thick. You'll notice the athwartship brace across the beam forward of the mast. Without the deck your vessel remains much like an open lifeboat as a structural unit.

I do recognize that many Morgan OI's have had spongy decks and they are difficult to repair if not kept up, but they don't represent a structural problem.

There are some other things that you might want to keep an eye on:
- The rudder in built with two halves (port and starboard) fitted together upon a foam core. Any slight damage from a grounding can cause a fault in this seal and some rudders have split open with one or both sides falling off. Inspect the rudder for any mid-line crack and it's best to add a fiberglass tabbing fully around the edge of the right and left halves of the rudder.
- The aluminum mast is likely stepped upon a steel plate. Many Out Island owners have had significant corrosion at the base of the mast. Care should be taken to form a barrier between these different metals at the mast step.
-Be sure to check for corrosion of the back up plate under the stem fitting where the fore stay is attached. Some have had significant corrosion here in this poorly ventilated area of the chain locker.
- Both of my Morgans were 1973 models and the fuel tanks were monel. I had to replace the two 55 gallon tanks on my 41' due to corrosion.
If your Morgan is of the 1976 or newer design, you probably don't have the large black rubber gaskets at the rub rail or the portlights. I replaced these due to leaks. I hope you have as much success and excellent cruising as we had with our Morgans.

[roberttigar]

The OI33 is a plywood deck-not balsa. I know becausde I have 1. Have mounted 2 vents on the deck in front of and either side of the mast. One is inside the head and the other is over the closet.
Not the toughest thing to do. Drill a pilot hole and cut with a sabre saw. Caulk the vent and screw it down. After 20 years-no leaks from the install. Bob

[Hudson Force]

Originally Posted by roberttigar

The OI33 is a plywood deck-not balsa..................... Bob

This is probably a variation by model or year of production. Both of my 1973 Morgan Out Islands had balsa cored decks.

[JimmyDarci]

Agree with above comments. Not on that boat, and don't fix it if it ain't broke. On the bright side, it sounds like you may have started building the beginning of your new boat.