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Post by dbostrom on Dec 4, 2014 3:43:47 GMT
I've been devouring the Jeanneau Owners Forum; there's a wealth of hard-earned make-specific info here. I feel much less as though I'm entering a forest of mystery. One of the topics I read with interest is the p-bracket repair described by Sailbleu, here.While crawling about in our boat the other day I ran across the p-bracket support and (once I'd worked out what it's for) it struck me as odd that something that might sometimes expect fairly huge leverage to be applied to it should join the hull pretty much at right angles and without any means to effectively spread load. I'm not sure of the hull thickness at that point but regardless of that, a right angle is a "stress riser" and can be expected to fail early in a taxing circumstances. Clearly that happened in Sailbleu's case; the fractures in the hull happened exactly as expected, at the corner formed by the perimeter of the box. Our boat cruises in area littered not only with crab pots and their floats and lines but also numerous dead heads, logs etc. washed out from coastal mountains. Broken appendages are a frequent occurrence for the unwary. The vessel is also used for charter quite a few weeks of the year so that's another risk factor when it comes to things that go bump. All this taken into account I think I'd like to put a nice spreading curve in the support structure for the p-bracket, using a buildup of cloth and resin or epoxy to ease the angle where the structure joins the hull, inside. It seems to me it would be better to do this than roll the dice on having to repeat Sailbleu's arduous repair experience*. Those corners just bother me a lot so I'd like to make them go away. I've not worked with fiberglass before. I've done some background reading but asking rarely hurts. Pardon me for asking what may seem clueless questions: -- Assuming the area I intend to work in is thoroughly cleaned (including light sanding) is it necessary to further remove any of the surface treatment inside the hull before doing layup of additional material? I've read some generalities about this but am wondering in particular about what Jeanneau uses inside this area of the hull. Is the white surface material in SailBleu's inside photos a cosmetic coating, or something more mechanically integrated with the hull? -- Considering this work is to be done in an area of the boat that is not cosmetically sensitive, it seems as though epoxy as opposed to polyester or vinylester resin be the best choice for this work. Is this reasonable? * I also found myself wondering if part of Sailbleu's breakage might have been due to the line cutter digging into the substantial rope he encountered, exerting a large side force by torque sent on as leverage on the bracket, thereby exposing the weakness of the stress concentrating support structure. Our boat also has a line cutter which is a good thing in general but might lead to unintended consequences if challenged hard.
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Post by dbostrom on Dec 4, 2014 8:40:25 GMT
Cleanup after another rope cutter losing a battle and thus the fixing of a p-bracket: coxengineering.sharepoint.com/Pages/Pbracket.aspxSome useful tips at the end about handling epoxy. I think Jeanneau made a better effort with the Big Box design. Odd they'd leave the breakaway corners; so close to optimal but not quite there.
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Post by sailbleu on Dec 4, 2014 14:57:42 GMT
Cleanup after another rope cutter losing a battle and thus the fixing of a p-bracket: coxengineering.sharepoint.com/Pages/Pbracket.aspxSome useful tips at the end about handling epoxy. I think Jeanneau made a better effort with the Big Box design. Odd they'd leave the breakaway corners; so close to optimal but not quite there. Great link dbostrom. I will get back to you with regards to your first post in this topic Regards PS: sorry for the note in the initial post , pushed the wrong button .
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Post by electricmonk on Dec 4, 2014 18:53:22 GMT
"Considering this work is to be done in an area of the boat that is not cosmetically sensitive, it seems as though epoxy as opposed to polyester or vinylester resin be the best choice for this work. Is this reasonable?"
Perfectly reasonable, epoxy is the material of choice for repairs regardless of the original material. A prepared chemically clean surface is all that's required, exactly as Sailbleu did it and a temperature above 15 deg C.
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Post by dbostrom on Dec 4, 2014 21:22:30 GMT
Thank you, electricmonk.
I'm wondering about the best way to build up a fillet. What I'd like to finish with is a wide, deep fillet that will carry the load from the p-bracket box to a significantly larger area and perimeter of hull, extending perhaps 5 cm. from the existing joint.
I see that it's typical to do the fillet fill for a tab joint or the like using solid epoxy paste. Considering the volume of the fillet I have in mind, I wonder if it would be better to use a composite of epoxy and glass for the fill, lending the body of the fillet more tensile strength. An epoxy-soaked roll of glass cloth seems as though it might be suitable for that. Is that a permissible arrangement?
I suppose doing an epoxy mix with loose fibers in it would accomplish somewhat the same thing. Any thoughts on this would be appreciated.
(What I read last night while looking into this further makes me a bit more determined to perform this improvement. Although they're considered fine hydrodynamic performers, p-brackets are also fairly notorious for being loosened or dislodged due to the frequent fragility with which they're joined to hulls. It's hard to exaggerate just how much big wood is floating around in the waters here, along with the ever-present crab pot floats and lines.)
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frankc64
Full Member
SO32 Owner - "Little Gull"
Posts: 40
Country: USA
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Post by frankc64 on Dec 5, 2014 3:59:08 GMT
It sounds to me like you basically would like to shore up the structure that retains the P-bracket. I'm no expert, but I've done a little fiberglass work and have built a couple of small boats and a canoe. One comment was that you were thinking 5cm, my thought is that if your going to take the effort to do this then 10cm or 15cm would take about as much effort as 5cm. In other words you might as well reinforce as much as practicable. Also, not sure of you exact configuration, but you might consider glassing in some marine plywood 90deg to the p-bracket - port and starboard I would think. Best to grab that moment arm as high as possible. I'm guessing that this is hidden under bunk boards anyway, so just go for it. Probably very enclosed space, so be wary of fumes . You'll want to wear gloves too, this stuff doesn't really wash off and will stick to your hands for weeks. For resin and fiberglass, I use a local shop - www.lbifiberglass.com. They probably don't need as much detail as you have provided here, but I think if you explain what your doing 'fiberglass fillet', they can provide better advice than I can give. I'd recommend that you have their web site open while on the phone. Prices are reasonable. Other outfits such as West System might do the same but that's a much bigger company, so I don't know. Good luck, Frank
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Post by dbostrom on Dec 5, 2014 5:56:51 GMT
Many thanks, Frank.
Whatever the exact final result I'll record the process w/photos etc.
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Post by electricmonk on Dec 5, 2014 12:50:41 GMT
Have a look at how Jeanneau strengthen the rudder post, basically a few pieces of marine ply glassed in as flanges, this would be easier to fabricate, larger and therefore stronger than just 5cm epoxy fillets. Two each side of the P bracket covered with 4 or maybe 5 layers of woven rovings would do the job I think.
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Post by MartyB on Dec 7, 2014 4:18:53 GMT
Is your boat local? or IIRC is it still south in Caribbean?
If local, ask the folks at CSR if they have any experience doing this. I would not be surprised if they have not done something like this.
Marty
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Post by dbostrom on Dec 7, 2014 4:58:14 GMT
Out of Bellingham, Washington since first in the water, Marty.
Deadheads and logs are our special problem here; the first hydrofoil service between Seattle and Victoria (back in the late '60s) ended with a quarter million dollar strike on a deadhead, the last of too many. There's fast boat service today; perhaps the crews are hypervigilant (fewer log rafts these days, too).
It's interesting to see a fair number of anecdotes in various places (Cruising Forum etc.) concerning rope cutters and large ropes. I think cutters are on balance a positive but it's odd how stories crop up about cutters encountering large rope with knock-on effects versus not so many stories of actual damage due to entanglement in props. One would think that leverage from a prop would be far worse. Maybe the cutter scenarios catch special attention and end up being told more often.
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Post by MartyB on Dec 8, 2014 14:54:08 GMT
Did you buy the 39iP that was for sale up that way?
The hydrofoil was late 70-early 80's IIRC. As my step dad designed a number of the bearings, including the BIG one that the front foil rotated on. Mom and he got married in 72, it was launched IIRC sometime after that. I would imagine a larger log found back in those days would screw something up big time. Have not hit anything to major, nor had any issues with kelp etc. in the prop. I did have a crab pot line get caught tween the upper rudder and hull one time. What a pain that was!
CSR may then be a bit of a way to go down here in Seattle. Not sure about MSC ie dealer in Anacortes if they have had issues or not, fixed in a way you are wondering about or not. There are three other yards there that might be able to do something besides MSC. I do not not know of any up in Bellingham. But know someone I can ask in a bit at an electronics class I am taking in Everett today. I'll try to have an answer tonight.
Marty
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Post by dbostrom on Dec 8, 2014 17:45:04 GMT
Yes, that's the one, Marty; "Kallisto." Unique circumstances led to my wife encouraging me to buy her; I'm still wondering if I've fallen into an alternate reality. I'll probably undertake this work myself as it's an opportunity to practice with fiberglass where few will see the result but I'd still be interested to hear recommendations. The foil I'm thinking of was Victoria, a vessel I ran across while looking for information on the old Princess Marguerite (the stylish way to travel to Victoria BC). See the July '69 issue of Motorboating magazine, strangely enough indexed and scanned into Google Books.
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Post by MartyB on Dec 9, 2014 4:47:58 GMT
If I had a few more $$$ in the pocket, I would have run up there! either the 36 or 39iP would be a semi first choice of a boat for myself, Ahead tho would be the SF35 or 37. With the 35 in front, then the 39, 36, 37 options....
Maybe I can talk the miss's into a 349.........
<Marty
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Post by dbostrom on Dec 16, 2014 7:41:10 GMT
Turns out I had myself all worked up about nothing on this. Could have sworn my attachment was identical to sailbleu's but it's not. The design has been substantially improved. Sometimes things do get better.
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Post by sailbleu on Dec 16, 2014 15:34:12 GMT
Hi dbostrom , good for you , saves me an extended explanation I did write one a few days ago , and believe or not , I pushed a wrong button and deleted the complete post. Not the first time that happened . Anyway that's one concern less for you , but now the weak link is the strut itself. They do break sometimes you know. Read a story on that some years ago. First thing that I'll do when on the hard again (I hope not the next 2 years) is change the cutless and volvo penta prop seal and remove the rope cutter . That type is a real disaster. Regards
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Post by dbostrom on Dec 16, 2014 19:53:12 GMT
...but now the weak link is the strut itself. They do break sometimes you know. Read a story on that some years ago. Aaagh! Too much information! You'll set me off again.
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