not to be …
‘For something to absorb impact it either has to be elastic (malleable) or it has to be crushed. Resin-soaked and hardened kev felt is neither’
steel is malleable and crushable…also HEAVY.
coefficient of restitution
resisting impact with materials largely depends on speed and weight limits.
Your communication skills…
really leave a lot to be desired. Much of the time I can’t tell what in creation you are actually saying. Confident I’m not the only one who feels this way.
Ignore this guy
Remember the time I tried to explain to him that cracks in gel coat due to a hull’s impact with a solid object were caused by the gel coat’s inability to flex as much as the underlying hull material? All the while he preached that cracks in the gel coat were proof that it had “absorbed energy” and thereby significantly reduced stress on the hull. I could explain the problem with that logic (again), but you get the idea.
how do you feel ?
The resin felt question:
If there is a less than resin filled felt but still cohesive before the impact…then hypothetically this product would offer more energy absorption than a filled felt.
Refer to crunchy candy bars
How that would be approached ? I dunno.
The OP’s hull has stem protection, my subject.
I agree others feel the same way. Probably most of Maine and some of New Hampshire.
Nonetheless ! the felts are on the stems.
cracks are evidence of energy absorption. The area absorbed energy and cracked. It’s eternal.
DK loves google
Google Datakoll. aka Gene something. And grab your beverage of choice. Its an eternal evening of reading how he has wrecked other forums.
He is doing a very good job on this one but I think and hope his time has run out.
But when it’s incidental and minimal, …
... you can ignore it.
Consider an eggshell. If you could coat your boat with eggshell, it would crack when the hull flexed, no matter how slightly it flexed. Yes, the eggshell would absorb energy when it cracked, but is it enough to matter? I say it's not. Gel coat is more flexible and a little stronger than that, but its flexural strength is still miniscule in comparison to any material from which a hull would be constructed. The stress it takes to make a paper-thin layer of gel coat break when flexed is so slight that you can (and should) ignore its contribution to strengthening the hull (or protecting it via energy absorption, as you prefer to say).
Using your logic, the paint on your car helps protect the metal when that metal is stressed. After all, the paint cracks if the metal bends more than little, so it must have absorbed energy, right? Well, you are right, but is it enough of a contribution to matter? Does your car benefit from the paint when you have a minor collision?
felt, gelcoat has the quality of absorbing energy then cracking or popping off and in that process protecting the laminate.
This is what happens. What you’re involved in is overstating a position in disagreement with a process that occurs and is foundational to your crit of it.
With gelcoat and felt stem protection, the facts are not negated on the VOLUME or DEGREE of the protection because the laws of physics state that the protection exists.
Try not to be dense?
Yeah - good idea. Speaking of dense, you might consider matters of degree. Put that steel on your stems and it won’t absorb any impact either - unless it’s density is such that it can be crushed (such as a “crush zone” provided by voids in the matrix ).
I can say something is malleable or not as a matter of degree (according to the force that can be reasonably expected to be appliied), and most people in the conversation will know what my point is…except for that one guy who has to divert from the point to avoid addressing the flaw in his ridiculous argument.
and that is a reason…
…to choose either over a stronger material?
That’s true, but you can’t see my point?
Using that same logic, I can truthfully state that when I jump off the ground, the whole earth moves in the opposite direction, and rebounds to its original position during the time that I fall back to the floor. There comes a point where theory, no matter how undeniable, is useless from any practical standpoint.
Steve gets it perfectly. Just because one material fails when bonded to a material with greater durability doesn't mean that failure is a desirable or intentional outcome. In this case, the design purpose of the gel coat is to take the wear of abrasion so that the structural material beneath doesn't. The fact that the gel coat cracks when the hull is flexed beyond a certain point is incidental, not a design feature, and not a benefit.
Excellent summary. n/p
Looks as if I should…
just skip right over his posts in the future. No sense feeding it.
As an aside, I hope you are doing well these days.
abrasion is impact
abrasion is impact abrasion is impact
stems are stems and keels are keels…no turning a stem argument into a keel argument
water flows downhill not uphill
recent reports from
report destructive inhalation of epoxy fumes
Only in your world, …
... and only once it otherwise would be unavoidable to back down from a premise. This whole time, and also the previous time, you did nothing but talk about breakage of the overlying material being a sign that it was doing what it was designed to do, and that the underlying material was significantly protected. Now you want to say that gradual wearing-away of the overlying material is exactly the same process? On other occasions you've tried to convince everyone that protecting the hull from hard contacts (which caused the gel coat to break) is what the gel coat is there for, and that any idea that it functioned as an ablative later was totally off the mark.
Go back and re-read (as if it will do any good) why I mentioned the old gel-coat topic. It has nothing to do with confusing stems with keels and everything to do with the other topic that popped up here (as mentioned on so many other message boards about you).
Dang - that was interesting.
But wait! The third entry is my post here, that begins with me saying "You're right, Datakoll".
Relax people - it was sarcasm.
I once had the idea that these types of internet troll were all the same person with different pseudonyms and sometimes slightly different shticks. But anymore, I think it's just a case of "dime a dozen". There seems to be nothing unique about them and they all seem to suffer from the same demon and use the same tactics, but each one is just another face in the crowd.
edit: No - I stand corrected. Gene may indeed be unique.
immutable. That research should defur to OC is intolerable in a 'free society.'
Your disagreement on free speech within discussion does not change physical laws.
I left San Jan when the local OC people, supported by the Sheriff and Weyerhaeuser employees but not the State/county government who allowed unlimited access.
The seismic - animal behavior research was done with an immediate opening for language left undone.
Super kayaking, wonderful hosts at SJCP in Luna and Fischbien. The local mob mind reader vigorously objected to my presence with the tour people behind her believing the Orca would learn English, 'go on TV' vigorously objecting to 'Orca Tourism.
I left when OC attacks began the 3rd year direct and physical not simply jolting me awake every hour.
This was the tour on the beach position with kayak tour people screaming at me and stealing my equipment.'
Here in Florida, I began a projected 3 month dolphin program with Tampa to St George pods. We are friends from my running on their beaches for 3 years recovering from a lung infection. The pods come up onto the beach to say hello.
St. George and East Point OC who would benefit from dolphin tourism threw me out with the State and Sheriff giving OC control of the area. Really ugly scene of screaming and threatening from the campground hosts and groundsmen. I was not about to shell out $1000 for prostitution services but the next camper of course would so I left. For good.
OC demanded $15000/year for the permit use of ???the state park system for dolphin research.
There were two other research programs intended for the State U but ...
I’ve got skid plates…
on almost every boat that I own. Some look they were professionally installed, others clearly were not. The biggest is on an old Mohawk Whitewater 16 – its thick like yours, and exhibits some of the separation and cracking that Peter discussed above.
The least functional is some sort of felt (kevlar?) that was installed at the factory on my Bell Yellowstone Solo. It was on the boat when I bought it new. After many years of use, I have worn through the stern skid plate and vinyl layer below, and I’m now at the ABS layer.
So much for abrasion resistance. I though I was being careful about dragging this boat around, but I guess not. I’m going to need to fix this at some point soon. I have a repair kit with fiberglass cloth - any thoughts on repair would be appreciated.
Personally, I’d just leave yours alone. It’s clearly not the best installation, but it does provide protection, and probably won’t look much better if you start tearing it off.
Depends on what you have available
and how much time or effort you want to put into it, Erik.
On whitewater boats with Kevlar felt skid plates it seems pretty commonplace for the edge of the thick, raised plate to catch going over rocky ledges and stuff. Then the plate starts to crack off in chunks at the forward edge progressively. You can mix up some thickened epoxy using silica powder and fill in any areas of missing Kevlar felt and lay a fillet of epoxy around the edge that can be sanded to a smooth feather which will lessen the tendency of the plate to catch.
Likewise, defects in a Kevlar felt plate that is still mostly intact can be filled in with thickened epoxy then sanded fair.
On the YS boat, I would do something before the ABS wears through into the foam core which is only a matter of time. If you press in over the exposed ABS with your thumb and it feels spongy, it is a good bet that the ABS is already thinned out.
If there is a significant depression where the Kevlar felt has been eroded away, I would level that with thickened epoxy. On Royalex boats, G Flex is better than conventional epoxy, but conventional epoxy will work. I like G Flex for filling in defects and depressions because it can be mixed up in very small batches, 1:1 by volume, by eye. This avoids wasting epoxy and is convenient because leveling a depressed area often requires multiple applications of small amounts of epoxy.
Once you have covered the exposed ABS and filled in any depression you can decide whether or not to cover the area with cloth. Covering it will certainly make the repair more durable. You can cut a piece of cloth big enough to cover the repair and overlap the intact plate. You will need to sand the plate and clean it first.
Personally if it were me, considering it is a nice boat, I would sand and clean up the entire plate, fill in the depression and sand it fair and flush, feather the edges of the plate using fillets of thickened epoxy if necessary so the cloth will lay down flat over the edge, and cover the entire plate with cloth that overlaps it slightly onto the adjacent hull.