Master Marine 28' stringer question

[doug42190b]

Hello,
I have a 28' Center Console -- Master Marine -- built in the early 80's for reverend Moon -- some may remember those boats. I have been refurbishing this boat for several years by using "professionals" in the area. So far it has been awful! After 5 years I basically have gotten the transom replaced -- now 2.5 inches with 3 sheets of 3/4 ply plus about a half inch outer and inner skin. I have an Armstrong Bracket (30" setback) mounted with twin 200 EFI Merc's. That is truly about as far a all of these years has gotten me -- and it was never a question of $$$$ -- it was difficulty finding people who wanted to work that were skilled. The big shops were not interested so I had to go to smaller shops. Well, now I have taken the project on. I read, and read, and read everything I can get my hands on -- and bought videos, watched U-Tube -- read every Forum I can find. Now I will finish this project. I will get my wife to upload the pictures because everytime I do it, they are huge.
I have now removed the entire deck -- 3/4 plywood with 1/8" glass underside and 1/4" galss on top -- most of the deck was delaminated due to open holes every where. When I had the transom done (5 years ago), I asked about the condition of the stringers -- "they're good" I was told -- this weekend I found out that they are mush (boat has been inside for 4 of the last 5 years -- not under cover, inside a building)!

So here is my first question -- there are 4 stringers -- two inner stringers are 12" tall and the best I can tell are 7/8" thick and 2 outer stringers -- each about 5" tall and about 7/8" thick (7/8" on both is the plywood, not including the roven). The inner stingers are almost 16' long and the outer striners about 12 feet long.

Is it possible to double thickness the inner stringers -- from 7/8 to 1.75 inches, same length, increasing the height from 12" to 15", and do away entirely with the outer stingers? The boat had an inner liner that I am removing and going with the sole (3/4" Douglas Fir, epoxy and glass both sides) from side to side, resting on cleats attached to the sides of the boat hull and to the tops of the stringers. Before, the deck "floated" on foam and was part of the liner. There are three bulheads currently -- one at each end of the gas cavity (96" apart) and then one 28" forward of the "forward" end of the gas cavity but all three are only between the inner stringers. There are no frames or bulkheads elsewhere in the boat. I am shifting the gas tank 16" forward to offset some of the weight from the bracket and two engines (boat designed for 1 - 250 HP I was told) so those bulkheads will be relocated and I will add one more for the new anchor locker (existing one is tiny). Do I need more bulkheads/frames? Can I safely go to 2 stringers instead of 4? Hull is designed for blue water and that is where I fish. Safety is primary concern. These are the most pressing issues.

[tech_support]

Is it possible to double thickness the inner stringers -- from 7/8 to 1.75 inches, same length, increasing the height from 12" to 15", and do away entirely with the outer stingers?

Sorry, its does not work that way. It not the thickness of the stringers that matter (for the purpose of the stringer a 1-1/2" thick stringer is not really any better than 3/4") , its their spacing and the "panel" size that matter.

Frames/bulkheads will help to stiffent up the hull. Taking out a set of stringers would need to be mitigated in some way, you can move the stringer locations around, but the span needs to be the same in order to get the same stiffness

[doug42190b]

If I understand you, then I should just stick with 4 stringers, in basically their same locations -- 7/8" and the same length -- increasing their height is not a plus or a minus? As far as frames -- since there are only trhe three bulkheads, should I build frames? There were none in the original hull. I will try to get pictures uploaded tonight. Do 7/8 stringers sound right? A little odd for what I have seen -- usually 3/4.
Thanks,
Doug

[tech_support]

its probably a metric panel, maybe 20mm. Does not matter exactly, go for 3/4" total. Make long stringers by laminating 2x3/8" or 2x9mm with epoxy and staggered joints .

Floor frames will help stiffen up the hull even more

[doug42190]

I have noticed that frames seem to be rather random in placement -- is there some generally accepted rule of thumb for placement? Every 36" or 30" -- thickness same as stringers -- can they be moved around to make under-deck fishboxes on the sides or dry storage areas -- or are they simply placed for hull stiffness?
Thanks,
Doug

[tech_support]

yes, you want to keep the same max span between frames

[doug42190]

Here she is as she was about 22 months ago in my backyard.






200 hp Mercs on Armstrong bracket


Interior shot as it started out -- before I knew what was lurking under the sole/deck.


Transom as installed by local glass guy -- it only took him 3.5 YEARS!




If you are not familiar with these hulls, I think I spoke some earlier but I'll double check, this "foot" on the front of the hull should (as others have told me, provide a "pound-less" ride in the chop. I can't wait to find out. I hope this will give everyone the "flavor" of the "canvas " I started with. I began in the summer of 2010 under my own efforts. After reading, studying, etc. everything I could, I decided "I can do this myself." I believed I would have it seaworthy by summer 2012.

[doug42190]

Please remember, I have done everything since it came into my backyard myself -- alone -- with no help -- with no one watching and asking me, "What ARE you doing???" "Why are you doing that or why aren't you doing this...???" I just jumped in -- I am a glutten (as you will see) for on the job training -- or, put another way, 1 step forward and 7 backwards.
I started out by removing the gas compartment hatch -- weighed about 100 pounds or more but bone dry -- drilled some small holes and perfect sawdust -- just 1" plywood glassed onto the original skin with what I now know is polyester and roving -- lots of roving!
I put that aside then and focused on the gas tank -- or at least the getting it out part. And I do have pictures of this whole era of work -- just not at my fingertips right now -- I will get them posted soon -- you really don't want to miss this. I didn't know that often gas tanks are larger than the opening they are supposed to come out of -- this tank turned out to be 4 inches longer and 2 inches wider than the opening -- I found this after 2 days of digging foam out and trying to break it free. Finally got it free and found out that it was bigger -- by handy tape measure was correct. This was when the first rot showed up -- when I cut the deck a few inches to get the tank out -- but it was just a small area of rot -- about 30" X 12 ". "I can fix that -- I remember reading how to do that and watching a nifty video." I won't go into how long that took, how much it cost, and how bad it looked -- but it was my first glass work -- surely I will get better.
No work for about 4 months -- when I went back to work on it again, I noticed the deck felt soft near my "repair" (starboard side) and it squeaked when I stepped on it (Port side). No problem, I can fix that. I will just cut those sections out and replace them with good wood, epoxy and glass. This is when it all started to go south.
I cut out the bad but realized if I cut a little more, I could make a rectangular repair that would be easier for me to do. But if I just made it a little bigger, I could replace that other area that now isn't looking so good -- and while I am at it, I could..... well, after three months of playing that tune, I cut about 75% of the deck out -- but I left those front compartments alone (very ala Mako) they are great -- why mess with them?

Yeah, I can just leave them -- no need to mess with them.


You already knew, didn't you? Yup, they are now part of the "Master Plan" -- whatever that is today.


I'll just start putting in some frames, raise the deck a little (I left a 5" border all the way around of the old deck to put the new deck on top of). Just some epoxy on top of the old 5" cleat, some tape to tab it in to the liner, and I will be on the water in no time!
So, I started to put her back together -- stringers are good -- I know because the guy who did the transom told me they were solid!


You will notice that the liner has now been removed. Why waste that deck space -- I will just cut that out and take the new deck all the way to the jull side and pick up several (almost 6) inches on each side. Cool!

So, perhaps a bit hasty, but I ordered everything I needed basically to finish the project. I had already bought new electronics almost 3 years ago (still in the box), etc., etc. But now I bought batteries, cables, wire, harnesses, binacle, shift and throttle cables, etc. The UPS guy was my new best friend -- I just mentioned the tip of the iceberg -- "Yes dear, that's just about everything I ordered -- I think." NOT! But I was on a roll. It was now early March and I was going to be fishing this boat by May or June -- or July -- well, it will get wet sometime in 2012!

[tech_support]

thanks for the pictures. Lets just take it one question at a time, although I do not see any questions yet

[doug42190]

Actually, I have been trying to get to a point where I can ask an intelligent question. As of last weekend, I found the stringers were actually wet and I decided to tear them out. I now have them out and they were soaked -- and delaminated for the first 10 feet or so -- wet the remainder of the stringer.



Sorry for the feet shots.



Currently I am removing the roven the factory used to attach the stringers. There does not appear to be any tabbing. The roven appears to be three or four layers -- some of it seemed to be used only for the stringers and some appeared to be placed on top of the hull layup.






This is a piece of the outer stringer, port side near the transom. Please remember, the transom is new, 2.5" thick with wood and glass.


A picture showing the bulkhead at the rear of the gas cavity.


As you can clearly see in this shot, there are at least 3 layers that I am having little difficulty getting pulled up.

Am I removing too much? It seems that once I get to this point, it is just glass. I think I am all the way down to the factory layup of the hull -- but what about all of the roven I am pulling out? The hull still feels very thick -- I cannot detect any difference -- I do have the boat on a bunk trailer and boat jacks under the transom and 2/3 of the way forward (4 jacks total). I will confess that "little difficulty" is a relative term -- since I went mideveil, it isn't too difficult -- 8 pound sledge and wood splitting wedge -- but it isn't a cake walk -- just too easy for my comfort. I have more pictures of the work I got done today that may put more light on the subject. Am I taking out too much? Do I need to put a layer of 1700 down to compensate for all that roven? (It is called roven -- isn't it -- or roving? I am not sure).