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| Coral Reefer http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=6730 |
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| Author: | kissmysail [ Mon May 14, 2007 7:04 am ] |
| Post subject: | Coral Reefer |
Coral reefer, I have a H16, real bad delam, almost the entire area in front of pylon, both hulls. I like your idea of repair, should I do the standard delam repair with epoxy first or just use foam only ? Sailboats are like pianos, do not like to see one die,, |
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| Author: | Coral Reefer [ Mon May 14, 2007 9:25 am ] |
| Post subject: | |
I went the delam repair first but I leave my boat on the beach and people have a tendency to sit on the front pontoons, the repair did not last so I fill the front of the hulls competely with the marine close cell polyureathane foam. This is my 4th season coming up and the repair is still rock solid. You can skip the delam repair because the foam will press the layers together. |
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| Author: | CBFryman [ Mon May 14, 2007 10:47 am ] |
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I like that idea, how much boyancy did you lose? |
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| Author: | Coral Reefer [ Mon May 14, 2007 11:10 am ] |
| Post subject: | |
Actually when I first posted this repair, I stated that it seemed to add flotation to the front of the boat and had less tendency to pitchpole. I was chasticed by someone saying that air was more boyant than the foam. They would probably be correct if the hobie's had an inner liner in which you could increase the air pressure inside the hull. Ever tried to hold a surfboard underwater? Well to answer your question regardless of what some say, yes I have more flotation and the stiffer hulls allow me to push the limits in the ocean with out fear of pitching. Plus the girls love to ride out on the hulls. Great view while sailing. |
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| Author: | pappastratos [ Mon May 14, 2007 2:49 pm ] |
| Post subject: | |
My sister lives in Melbourne 1 or 2 hours south of where Coral Reefer lives. Their ocean is pretty rough sometimes, 4-6' seas, if his Hobie will survive that, it must be a good repair,, |
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| Author: | kissmysail [ Wed May 16, 2007 7:43 am ] |
| Post subject: | |
How much 4 lb foam did you use ? |
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| Author: | Coral Reefer [ Wed May 16, 2007 7:57 am ] |
| Post subject: | |
Foam comes in 2, 1 gal cont.( foam & harderner) and will fill 1 hull from tip to front pylon, I used 2 sets. Adds 16lbs to each hull ( 4cu ft x 4lb). You may want to go with the 2 lb. The 4 lb is a lot harder that the manufacturer describes. I believe the 2lb is going to be very hard also and you only add 8 lbs of weight to each hull. Up to you... if I was going to do over I would use the 2lb. Just to give you an idea of how hard 4 lb is, you cannot push a screwdriver through the foam, have to hit it with a hammer. Good luck... |
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| Author: | mmiller [ Wed May 16, 2007 9:02 am ] |
| Post subject: | Delamination Warning |
CBFryman wrote: I like that idea, how much buoyancy did you lose?
4 pound foam... volume, 4 pounds per "Qubic" foot. That's a lot of weight added forward. With this idea you are depending on the foam for structural strength. I do not advise it, nor do I advise sailing any cat with delamination issues that are not properly addressed / repaired. Especially ahead of the front beam. This is a very serious structural issue and not one to be taken lightly. Failure of a bow will leave you helpless in the water with a completely unusable boat. The only repair I feel comfortable with is the epoxy injection outlined in our FAQ and support area. |
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| Author: | Coral Reefer [ Wed May 16, 2007 9:12 am ] |
| Post subject: | |
Its 4 lbs per cubic ft. There are 4 cubic ft from the tip to the pylon. Only added 16 lbs to the hull spread out from the tip to the pylon. Majority of weight is at the pylon because hull has the most volume there. I haven't had any stress cracking in the gel coat or in the hull structure. My boat takes a pounding in the ocean, its held up fine for 3 years now. |
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| Author: | MBounds [ Wed May 16, 2007 9:18 am ] |
| Post subject: | |
4 lb foam = 4 lbs / cubic foot Air = 0.0768 lbs / cubic foot So for every cubic foot of foam you added, you added 3.9232 lbs to the boat. Since bouyancy = weight, you actually gained bouyancy, but by putting the all the weight ahead of the front pylon, you moved the CG of the boat forward, making it more likely to pitchpole. |
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| Author: | Coral Reefer [ Wed May 16, 2007 9:33 am ] |
| Post subject: | |
Then why am I not constantly pitchpoling? I solo my boat all the time and ( with GPS) in a 12 to 15KT wind manage 21 to 23 MPH in a 2 to 4 foot sea, I don't pitch nor worry about it and I drive the points down, water flying like shot out of a canon. Does your calcuation take in the bouyancy in saltwater? |
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| Author: | MBounds [ Wed May 16, 2007 10:43 am ] |
| Post subject: | |
Naval Architecture 201: Buoyancy is not a property of water, therefore, salt water does not have more buoyancy than fresh. Buoyancy is the upward force created by a difference in densities when an object is placed in the fluid. (The object does not have to be lighter than the fluid to have buoyancy - a rock weighs less underwater than is does in air - because water is denser than air - which is also a fluid, albeit a compressible one.) For an object that floats, the weight of the object = the weight of the fluid diplaced by the object. Salt water is more dense than fresh water: Fresh water = 62.4 lbs / cu ft Salt water = 64.0 lbs / cu ft All that means is that the boat floats higher (displaces less volume, but the same weight) in salt water vs. fresh. A fully loaded Hobie 16 (330 lb boat; 285 lb crew) displaces about 9.61 cu. ft. of salt water or 9.86 cu ft of fresh water. The difference (about 0.25 cu ft) divided by the water plane area (I don't have a good guess on that - but just use 4 sq ft for argument's sake) is the difference in draft. In this case, about 0.75 inches. Dynamically, a boat will feel "livlier" in salt water, because all forms of drag are reduced (surface, form, wave-making) and motions (pitch, roll, yaw, surge, sway, heave) are damped more rapidly. Back to the pitchpoling question, though. I'm not sure the added weight is making that much of a difference in the boat's tendency to pitchpole. Logic says it's making *some* difference, but in actuality, the extra weight is small in comparison to the rest of the boat and your butt sitting on the back corner casting. |
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| Author: | Coral Reefer [ Wed May 16, 2007 11:19 am ] |
| Post subject: | |
Exactly!!! But at that speed and wind, me and my butt are way behind the back casting only my feet are on the boat. Also, I should mention that my mast is raked to the max. Thanks, Hobie's are made to sail like your hair is on fire and I never get tired of that feeling, been sailing Hobie's since 71. |
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| Author: | pappastratos [ Fri May 18, 2007 9:47 am ] |
| Post subject: | |
Coral reefer, every time this comes up you take a beating !! I understand all the concerns, delam, epoxy, pitchpole, etc,, but this repair has worked for you in rough seas ! I have swam in the ocean at Melbourne Beach & have seen how big the waves are sometimes !! I believe I will foam mine, then maybe shoot some epoxy in delam area,, |
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| Author: | Coral Reefer [ Fri May 18, 2007 11:02 am ] |
| Post subject: | |
I don't mind. What they don't understand is that my boat is a 76, hulls were mostly shot, delam fix would not work for me. My choice was to find a way to keep her sailing or get new hulls. I have a friend who works for boston whaler and turn me on to the foam which they use. I don't race, I sail for pure fun. I really don't care if on paper this dosen't work, but in my world, I don't experience the problems of which they talk about. Boat floats, goes fast and i don't get pitched. What can I say... |
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