O'Day 25 Bulkhead Alteration

[jdratlif]

Hi Everyone,
I am new to the site and new to being a larger boat owner. I just recently bought an O'Day 25 and want to do some winter work to it. What I want to do is modify the forward starboard bulkhead to extend the V-berth bunk. I want to cut a section out of the bulkhead to to allow for myself to comfortably sleep on the starboard side of the V-berth. For some background, the previous owner replaced the aft bulkheads and never reinstalled the starboard vanity. With that, the space aft of the forward bulkhead is open making less work for myself.

I basically want to cut a section out of the bulkhead that will start from where the bunk's top is and extend the cut upward to the deck of the boat. I want to leave 8"s of bulkhead between the cut and the hull while extending the cut upward and leaving over 12"s of bulk head between the ceiling and the cut. The section cut will resemble a misshaped "C". I will then reinforce the entire bulkhead with a piece of 1" thick finish plywood. After all of that I will extend the bunk by about 1 foot.

I have been analyzing the structural intent of this bulkhead and do not see a problem with this. I do have a background in simple structural analysis. The bulkhead, I want to modify, does not contain the chain-plates for the starboard stays or any exterior holdings. From what I can tell is the bulkhead is mainly for Hull reinforcement from the pressures exerted on it during normal use. Also, I feel that the bulkhead itself is not critical to holding the weight on the deck because the decks shape and thickness allow for it to be sufficient in supporting the operating loads.

I understand I am new to boats and understand there is alot that I do not know. With that being said, I am not the kind of person to not do things because of scared logic. I believe there is an analytical approach to most problems and believe in discussions that detail all solutions to problems.

I am posting this modification idea because I want to know what other people with boating experience think of this? I know there could be alot of things I am overlooking and hope that I can be pointed in the right direction with this.

Thanks in advance for the help,

 

[Joe11688]

As long as the mast tabernacle has good support, I don't see why you can't follow through with your plan. I love sleeping in the V berth area of my O'Day 222. I'd do the same thing if I had to. Just be sure you're right, and then go ahead. Post some pics when you get a chance.
Joe

 

[jdratlif]

Thanks for the reply. The mast tabernacle is supported with the BH kitty corner to the BH I want to alter so I believe the mast is adequately supported. If anyone knows of any books that explain the design of bulkheads I would love the suggestions.

I am currently in the investigation/planning phase of the alteration but I definitely plan on taking pictures and documenting what I do. When I do this I will post what I have completed.

Thanks again

 

[Joe11688]

Years ago, I installed O'Day 25 chain plates on the main bulkhead of my O'Day 222. I beefed up the bulkhead on the V berth side with oak boards and bolted them to the settees. I had to cut slots in the fiberglass edge of the V birth on both sides to accommodate these boards. My bulkhead is very strong now.
Later on, I had covers made up and welded to the chain plates and bolted through the deck on each side of the boat with metal backup plates. The chain plates are even stronger now and the welded chain plate covers seal out moisture. So I guess I can say, "been there, done that."
About three years ago I removed every piece of wood from my cabin including all the bulkheads and refinished it to a dark red Mahogany color. I made a drastic change to the galley cabinet and got rid of that hideous fiberglass sink and stove insert and added a new stainless steel sink. My stove sits on top of a stainless steel steam table pan which is screwed to the top of the cabinet and I was able to create a new storage under it for all my pots and pans. It worked out great. I also relocated my galley pump to the left side of the sink so that I can avoid getting burned by my stove-top oven when it's in use. I think a lot of those pics may be on this site under "Trinkka's Mods."
It's good to think out a project first before you tackle it, just to be on the safe side, but when I want to do something to my boat I usually go right ahead and do it if I think it will work.
The scariest job I ever did in the cabin of my boat was the day I made my Teak companionway step detachable. I needed to be able to get a 50 quart cooler behind this step and I could do that with a detachable step. After I cut a square hole in the top of the two fiberglass mounts, there was no turning back. It all worked out great after I mocked it up with cheap scrap wood and then finished it off with Teak and two metal adjusters. It came out better than expected and it looks very decent considering that I'm kind of a hack when it comes to finish boat carpentry. I've done about 30 mods on my boat. Some came out good and others not so great but they were all fun to do at the time. Good luck!
Joe

 

[RON CULP]

Joe I Can't Belive How Much Knowledge You Have On Oday Boats..
I Want To Put Pictures On My Site (one Of Myself) Will Get It
Worked Out Eventually.

 

[Shoaldrafter]

Bulkhead Alteration

Thanks for the reply. The mast tabernacle is supported with the BH kitty corner to the BH I want to alter so I believe the mast is adequately supported. If anyone knows of any books that explain the design of bulkheads I would love the suggestions.

I am currently in the investigation/planning phase of the alteration but I definitely plan on taking pictures and documenting what I do. When I do this I will post what I have completed.

Thanks again

Ron said he is new to boats and wants to modify bulkheads on sailboat, specifically an O25.

First, here is a place that has a program to teach you what effect you might be having:

http://www.westlawn.edu/

Understand that a very good naval architech designed the O'Day 25. Bulkheads were place where they were have study and computation of loads and stresses under sail. Bulkheads do not just internally divide a boat. Bulkheads support more than the mast. They maintain shape of boat in water which under sail exerts tremendous pressures against hull. If you look further you will find several partial bulkheads on your boat. An you will find stringers and strongbacks.

You best be able to evaluate the loads on the hull where you weaken any bulkhead. Just imagine the boat caving in while in the middle of a lake when a heavy gust of wind hits it. Down you go to davy jones locker...

You are not just messing with verticle pressures but lateral pressures. Because the bulkhead you are playing with is foreward of the mast does not for one minute that it is not handling a significant load from the mast.

Maybe you need to make a small table to put in the accessway for your feet?

Think twice before sailing with the modifications you describe.

Ed K
O26

 

[jdratlif]

Re: Bulkhead Alteration

Ed,
I really do appreciate your reply to my post. However, your thought and post on my bulkhead alteration is not what I was looking for. I understand that what I want to do is changing the structural integrity of the boat, especially the hull. What I am asking for are actual examples for what I should be looking for when planning for this modification. Bashing an idea by just saying a naval architect designed the boat, and that is that, is not a rational argument for why someone should not do something. Engineers are only people, and just because they design something one way does not mean there are not other options for similar designs. I know this because I am an engineer. I am using this website to pool the experience and knowledge, of boat owners with more knowledge then me, to help in my investigation/planning phase. Posts, like the one you just left, only hinder competent discussions from taking place. I just hope that your post's complete lack in faith in this project does not deter anyone else from giving logical "cons" to this project.

Josh

 

[Joe11688]

Joe I Can't Belive How Much Knowledge You Have On Oday Boats..
I Want To Put Pictures On My Site (one Of Myself) Will Get It
Worked Out Eventually.

Ron,
I live about 10 miles from Rudy Nickerson's store and every once in a while when I stop in to buy something that I need, I pick his brains. Outside of that, I don't think there are too many things on my boat that I haven't taken apart. The hardware that I did remove needed attention otherwise I would have left it alone. Thank God I've never had to remove my bow rail, stern rail, or any of the stanchions. It takes two people to work these things and you break a lot of stainless steel bolts in the process.
I really love my boat and I keep striving to make it better every year. So between picking Rudy's brains about my boat and other O'Day boats, and taking my boat apart through the years, I've learned a little about everything. You could say I'm a jack of all trades who never mastered any of them. I classify my work as being- "a little bit above below average"- like my guitar playing. Good luck Ron! I look forward to seeing your pics.
Joe

 

[Joe11688]

Re: Bulkhead Alteration

I don't know that I would go along with your summary on this Ed. Most of these O'Day Sailboats have strong thick hulls. The fact that they can take a complete roller trailer offers plenty of proof to this fact. I think that if Josh really knows his boat in the same way that I know mine, he should be able to do what he wants to do with no problem. Anyway, he is asking if anyone has ever done this to their boat and if so, have they been successful. There may be someone out there who has done this to their 25. If not, he can be the first guy to start a new and different mod on his boat and show others how he did it.

 

[Shoaldrafter]

Captain Fuzzy

I don't know that I would go along with your summary on this Ed. Most of these O'Day Sailboats have strong thick hulls. The fact that they can take a complete roller trailer offers plenty of proof to this fact. I think that if Josh really knows his boat in the same way that I know mine, he should be able to do what he wants to do with no problem. Anyway, he is asking if anyone has ever done this to their boat and if so, have they been successful. There may be someone out there who has done this to their 25. If not, he can be the first guy to start a new and different mod on his boat and show others how he did it.

Captain Fuzzy,

If you go back to my post, I did not say not to do it.

In closing I said think twice. Previously I said, "You best be able to evaluate the loads on the hull where you weaken any bulkhead."

I gave Westlawn as a place to learn how to calculate loads. He is dealing with a boat how old? Just being a heavy old boat does not translate to being able to handle potiential loads.

No it would not sink on water with the fore bulkheads. At least not on a quiet sunny afternoon with winds of 5 knots. But as experienced sailor, have have you had to make headway in winds of 20 knots? A quick storm that came up?

Do the waves knock the boat around?

I do not and did not say not to make internal changes. However, calculate what the effects of what you are doing are going to be.

As an illustration, old sails and wind gusts. Have you seen any sails torn to shreds in winds? Consider that the sides of a plastic boat are just thick materials akin to sails. Consider that water pressure of waves can exert knock down forces. Just consider the numbers of the forces and whether the materials are able to handle those numbers. Understand that John Denatel the designer of the O25 did consider those forces. That is why there is a bulkhead there.

The bulkhead has a lot more reasons than just holding up the cabin roof. And the bulkhead placement is similar to many other boats of similar size. I would say that many n.a.'s considered the forces involved.

As an altenative, consider reading this:
http://www.boatdesign.net/forums/sailboats/sailboat-bulkhead-layout-deck-design-24205.html

Captain Fuzzy, I believe you took your boat out of the water? Do you have a favorite reading chair, a rocker by the fire? Consider reading Ted Brewer Explains sailboat design or Crusing Sailboat Kinetics by Danny Greene.

But all the above does not say that is the only place for the bulkhead. Just the forces do have effects. Think of the bulkhead placements in the Titanic.

Ed K


O26

 

[Joe11688]

Re: Captain Fuzzy

That sounds good to me Ed. He says he is an engineer and I'm sure that he'll calculate the loads. I had both of those books that you mentioned. My late pal and fellow YC member Walter was interested in sailboat design and when we lost him I inherited his whole book collection, all 125 of them. Those two books that you mentioned were in that collection and I donated them to my city public library. Some of them I kept and the rest went to our YC yard sale and the local USPS in which Walter was a member. I can't get interested in sailboat design. It's too dry.
Ahoy!
Fuzzy

 

[emergpa1]

Josh,
Don't take the post too hard. I received a lot of flak when I posted a similar idea to modify my main bulkhead and eliminate my for'ard bulkhead. ( That sinking feelin'..trouble with compression post, i think that is the thread> you can also see the pics on my album )
I can't really add any wisdom except maybe, maybe this....I think there is a good chance that reducing the bulkhead structure will reduce strength.
So i guess the question is..do you need the strength??????? I mean, I don't where i sail! Heck, if my boat sunk i could swim the 100 yard it would take to be able to stand up and walk the rest of the way to the shore...on the other hand, if subject to large wind and wave some distance from Tera firma then harken unto Ed K's voice.
HAVE FUN
Keith

 

[25yearslater]

Josh, when I looked at 25's and 27's the forward bulkheads are virtually identical. They are attached only by the 4 sheet metal screws into the v-bunk platform. That platform appears to be the lateral support for the forward hull section. The upper part of that bulkhead floats in the cabin liner combing. The vanity is only tied in by about 4 screws from the starboard main bulkhead to the forward 'privacy' bulkhead. See the welting on the edge of that bulkhead? It's not tabbed to the hull. With the vanity already removed any structural component has been proven minimal. You might even gain some extra strength in the chainplate bulkhead by extending the berth to it. If it turns out to be a crap idea I'll send you my decorative teak bulkheads for the cost of shipping to replace what you remove or cut out. Keep me in da loop. Joe

 

[Shoaldrafter]

Joe of 25 years later

Josh, when I looked at 25's and 27's the forward bulkheads are virtually identical. They are attached only by the 4 sheet metal screws into the v-bunk platform. That platform appears to be the lateral support for the forward hull section. The upper part of that bulkhead floats in the cabin liner combing. The vanity is only tied in by about 4 screws from the starboard main bulkhead to the forward 'privacy' bulkhead. See the welting on the edge of that bulkhead? It's not tabbed to the hull. With the vanity already removed any structural component has been proven minimal. You might even gain some extra strength in the chainplate bulkhead by extending the berth to it. If it turns out to be a crap idea I'll send you my decorative teak bulkheads for the cost of shipping to replace what you remove or cut out. Keep me in da loop. Joe

Joe,
Do not assume that loose bulkheads as discribed above do not provide all kinds of support or boat shape under specific conditions. Under wind, sail, and water pressures a fiberglass hull flexes. It it might very well be that the designer, in this case John Denatel, understood that a certain amount of flex was o.k., after which the bulkhead was needed.

Or it was o.k. to flex a certain amount bumping the dock, but after which the bump concavity was permanent?

These boats are still around because the designer was good. And last I heard he was still kicking. I do not say changes cannot be made. I do say understand the forces involved for safety of others. That is the captains marine responsibilty.

Ed K
O26

 

[25yearslater]

Hi Ed. I wouldn't be so bold as to assume anything. I have been studying the construction of my 27 for anything indicative of problems. With a 1/2" gap at the top of these bulkheads any flexing would be evidenced by chafe were the hull liner passes behind them or the welting failing. Some chafe would also be apparent within the combing. I have found none of this to be the case. Couple this with the shear of a few #10 sheet metal screws 1/4" from the bottom of plywood and I personally would have opted for at least a backing plate if my intent was to provide structural support. Again it is entirely possible this provided a minimal amount of support but I still believe it's main function was to isolate the head from the v-berth area. In fact if I could have matched the plywood colors on my project I would not have hesitated to use the decorative plywood for this area. All my best, Joe