Master Marine 28' stringer question

[tech_support]

Can you give me some idea where you would put the stiffener?

right in the middle of the span, between chine and sheer

The PVC pipe for the stiffener -- 3" cut in half? 4" cut in half? Should it run from basically the transom all the way to the bow (or pretty close to it)?

you can end/start just shy of either end, or take it to the end, either way.

i would use the largest I could without interfering with anythign else. A 4" is much stiffer than a 3"

i would use light weight PVC (irrigation grade). make some slices if needed to allow it to take curves (if need be). One layer of 1708 will do the job.

below is a shot of a center stiffener/drain tube on my seacraft. I used two layer of 1708, basically just overlapping on top of the pipe.

[doug42190]

Shine,
Thanks. very clear. Thanks also for the picture; that helps.
Doug

[doug42190]

Pictures to follow soon; I left the camera at the office.
Yesterday (Monday) I got the 4th stringer installed -- YEA!!! All 4 are in now with all 4 filleted and tabbed -- three layers of 12 ounce, wet on wet. I have decided to use 4" PVC cut in half for side stiffeners, filleted and then covered with two layers of 1708, staggered 6" and 10" beyond each edge of the PVC. Next it is back to the stringers to trim and make sure they are level from end to end. Early measurements show that the inner stringers are a little off -- starboard is level fore and aft but the port didn't end up that way -- have to remove some from the stern end and compensate about the same on the bow end (almost 7/8"). The center point of the two are level (beamwise). I realized that when I raised the stringer off of the hull to prevent hard spots that I must have messed up and raised the rear too much and I didn't catch it until I was almost through with the fillet -- I believed it would be less work and cheaper to just trim the stringer once I finished -- then it is on to cleats on the hull side and on the stringers!
Question(s): I am considering using 3/4" fir for cleats on the hull sides and the stringers. Is one layer 3/4" thick sufficient for cleats and is there any reason -- pros or cons -- to making the cleats around the hull one continuous run as opposed to 12" blocks with 4" spaces (or something like that)? I was also considering doubling the thickness but it that too much? How tall should they be -- 2" more/less? Lastly, is it necessary to run "floor frames" from the inner stringer to the outer stringer AND from the outer stringer to the chine/hull side? I ask because from the outer stringer to the chine/side will also be filled with 2 pound foam for the sole to ride on as well as some stiffening, sound deadening, and flotation uses. Please keep in mind I removed the inner liner and I will not be putting it back.
Thanks for any input.
Doug

[FitzFisher]

I am considering using 3/4" fir for cleats on the hull sides and the stringers. Is one layer 3/4" thick sufficient for cleats and is there any reason -- pros or cons -- to making the cleats around the hull one continuous run as opposed to 12" blocks with 4" spaces (or something like that)? I was also considering doubling the thickness but it that too much? How tall should they be -- 2" more/less?

I use 1x2 pine and cut 6" lengths spaced about 4 inches apart. I like the idea of straight lumber for this job so you aren't realying on the composition of the ply wood to hold up and not peel off. It isn't really designed for that kind of load, plus the 1" stock is really cheap and holds up great if you just paint it with a coat of resin. I can't see ay advantage to doing more than that as you are really only supporting the edge (in combination with your topside tabbing)

Lastly, is it necessary to run "floor frames" from the inner stringer to the outer stringer AND from the outer stringer to the chine/hull side? I ask because from the outer stringer to the chine/side will also be filled with 2 pound foam for the sole to ride on as well as some stiffening, sound deadening, and flotation uses. Please keep in mind I removed the inner liner and I will not be putting it back.

As you can see in my build, I am a strong believer in the full transverse frames. It adds a lot of stiffness and also helps support long spans of the floor. It is really hard to get your foam to form perfectly up against the floor and over time it will get tamped down and compressed, so I don't think 2# foam will offer much long term "Support". It might be good to do a scaled layout of your boat to show where you will have bulkheads and frames etc., so Shine and the pros can see what your spans are. That will make a big difference on the thickness of ply needed for the floors, the need for stiffeners,and or the recommended spacing of the frames. You can do a pretty good mock up in "Paint" and show the planned dimensions. None of that will have much effect on replacing the inner liner. That will be addressed by your addition of the side stiffeners and cap.

Regarding your stringers, you can use a cross hair level or go old school and make a string grid to lay out your stringer and frame heights. Nice long straight edges are really handy when you are figuring that all out too.

Keep up the hard work!

[doug42190]

Fitz,
As always, thanks for dropping by and your insights. They always help me see things from a different angle. I do have a small laser level (torpedo) that has been helpful but I am often at a loss has to how to accomplish things that I know I need to do -- setting these heights and getting them "all the same" was becoming frustrating but your idea about the string helped me see a way to do it and use the laser level -- but not just the laser level.
The thoughts on the foam are good too. Just a thought -- do you think it would be worthwhile to foam those areas with 4 pound foam or even 8 pound so it would be more rigid and wouldn't get packed down? Or is that not worth the extra money/weight?
Also, what kind of dimensional lumber did you use for the cleats (oops, reread your response -- pine)? I assume that 1X2 is actually 3/4" X 1.5" or some such nonsense -- did you put multiple layers of epoxy -- like 2 or 3 and then peanut butter them to the sides and fillet/tabb them, too? Did you also use the dimensional lumber for the stringer cleats and for stiffeners (I think I saw some were plywood on edge but I am not sure)?
Time to go read through yours and Shine's again to get myself up to speed for the next phase.
By the way, how did the motorcycle race go this past Sunday?

Thank you,
Doug

[doug42190]

Pictures of latest work to follow but here is a freehand drawing showing my intentions -- I hope we can read it. Any thoughts or suggestions?


Sorry about the size but I wasn't able to read the smaller size -- probably operator error
Doug

[FitzFisher]

Hey Doug,

do you think it would be worthwhile to foam those areas with 4 pound foam or even 8 pound so it would be more rigid and wouldn't get packed down? Or is that not worth the extra money/weight?

I don't really have any experience with that, but it seems like if you try to fill it and cut it down level like I did, your're not really going to get a real tight support. Maybe if you poured it though holes in form boards with holes cut in and weighted them down real good you could get it to fill perfectly, but I never got the hang of that technique. Plus all the extra expense and weight all may not really be worth it if you are doing 36" frame spacing and use a good quality plywood for the sole. Are you going 3/4"or 1/2" with stiffeners like I did? You might be able to go more high tech and use foam boards or something. Good questions for Larry and Jacques and Shine.

I assume that 1X2 is actually 3/4" X 1.5" or some such nonsense -- did you put multiple layers of epoxy -- like 2 or 3 and then peanut butter them to the sides and fillet/tabb them, too? Did you also use the dimensional lumber for the stringer cleats and for stiffeners

Yes I used the 3/4 X 1.75 or what ever it is. I may have used 1x 3 and ripped em down to 2" on the table saw actually. I just used one good coat of epoxy and the pb. Almost all of my compartments are completely sealed, so I don't expect much moisture attacking those pieces. I did use 3/4 marine fir plywood cut in 2" strips laid on end to make the stiffeners, but those were coated in epoxy, glued with PB and then covered with 6-10oz cloth. and in cases where there would be moisture, coated again with tinted epoxy.

The bike race was great. I finished 7th out of 42 riders in my class. See this link for a cool view of one of the obstacles in the "hard" line https://www.dropbox.com/s/460ugtdxmw3kx31/WallPt1.mov This one had me puckering every time!

I hope to finish glassing in my decks tomorrow and start on the rear cabinets and topside of the gunwhales....Have a good weekend.

[doug42190]

Fitz,
Thanks for the comments and help -- I really appreciate it.
Great video! I saw that same view many years ago. I raced motocross for 1 year -- I had a Honda Elsinore -- one of the first in Virginia showrooms. Badazz scooter for that size (250cc) and a hightech bike for the year -- 1972 or 73 -- never got very good at it but it was a lot of fun -- at times.
You made a couple of good points about the foam -- I am going to consider the plywood with holes but I am leaning to just an open area pour and level it out, probably a coat or two of epoxy, and be done with it. I think I am going to at least try to seal mine up tight, too as I would rather not deal with putting limber holes in the floor frames and stringers, etc.
My plan was/is to use 3/4" fir for the sole with epoxy and a couple layers of glass on the top side and epoxy and 1 layer of glass (maybe 1708 or 1808) on the underside. I am considering making all of the hatches out of 1/2" to save some weight and some money. I am getting ready to go back and read some builds to get more ideas about the weight of cloth folks used for covering the sole. In using 1/2 for your sole -- how much money and weight do you estimate you saved? I know there is a big difference between a 21' and a 28' but just curious. The weight doesn't bother me probably as much as it might you as I have twin 200's to push it -- I don't want to get crazy with it, but I am much more interested in making sure it is stiff and strong more than the weight -- I fish the gulf stream and depending which inlet I go out of it is between 42 (outerbanks) and 75 (Virginia Beach) miles each way!
I will be watching this part especially close -- I am starting to think about what I want to do in those very areas!
We (my wife and I) are coming to Port St. Lucie (I hope I spelled it right) the very end of December for the New Year. I have no idea where you are in relation to that, but if it is doable it would be great to meet you and see the 'poon chaser -- and maybe buy you what we call a "long neck ice tea" when you are avoiding the beer word. Personally I don't drink, but it doesn't mean I can't buy you one.
Catch you later and have a good one.
Doug

[fishead6]

Doug,

Thanks for picking up the Composites order...I need more already. Looking good so far. Any updates for the 10 days you've been back?

Andy

[doug42190]

Hey Andy, thanks for dropping by. Perhaps if we get a large enough order together, we can just make a road trip for more supplies. Had to pay sales tax but that was a lot cheaper than the shipping!
Yes, I have gotten a fair amount done since I got back.I will try to load some pictures tonight (if I get home before 8:30).
I have 2 layers of glass over the port-inside stringer -- 17 ounce biax (no mat) and another layer of 12 ounce biax (no mat). Shine recommended 1 layer of 1708 (24 ounces) or 2 layers of 12 ounce (Stronger and easier to work with). I didn't have enough 12 ounce so I went with 17 ounce and 12 ounce. Should be bullet proof! I have the layer of 17 ounce on the port-outside and the 12 cut and ready -- leaving for work at 7:15 and getting home at 8:30-9:00 has put a crimp in weeknight work. This weekend I expect my 14 year old granddaughter to be here -- she was a great deal of help late last year -- 4 hands are better than 2! So my hope is to get all stringers covered with all layers this weekend. Then the more fun stuff will start where you really can see a difference. Putting 2 layers of glass on a stringer already in place really doesn't show how much work went into getting it to that point -- grinding, vacuuming, wiping with acetone, etc. when you look in the hull -- not like adding pieces and parts where new stuff is showing.
So hopefully next weekend I will be putting in bulkheads, floor frames, rigging tubes, drill holes for thru-hulls like high speed pickup, transducer, etc. Then it will really start to excite me!
Thanks,
Doug