Keel abrasive protection, HDPE

[PAR]

There are typical application needs for HDPE and other high modulus plastics. The usual course is just to employ elongated slots for the fasteners or a track system. I like these inert plastics, but they, like everything else require application specific approaches to attach them.

 

[viking north]

In the case of plastic lumbered patio decks, cross sectional "H" shaped and screw fastened 2in. long plastic slider clips are used. These allow the deck planks to move longitudionally to compensate for the temp. induced dimensional changes. As PAR referred above, some similar setup would also have to be used in the OP's application. How to achieve this without mechanical attachment (The OP frowned upon using screws punching holes in his hulls sealed surface) will be a challenge. The other concern I would have is the added drag factor created by this fastening system interrupting the normal clean flow of water along the rubbing strakes themselves. Since polyester/epoxy bog or antifouling does not adhere well to solid plastics but does so to FRP, the process of elimination would again steer me in that products direction. One can have one's cake and eat it too, I.E. Non mechanical fastening (Epoxy Bog) plus good antifouling adherence. The labour intensive, on my back, overhead, cramped working space, install, I would not look forward to.

 

[viking north]

Old age must be catching up on me and possibly it was mentioned before (Only scanned the thread) but if FRP rubbing strakes are used it will not be necessary to remove them for wear replacement. Simply rebuild the wear areas on site by adding a few layers of resin and glass.

 

[jonr]

Supposedly 3M's DP-8005 will achieve full strength UHMW-PE bonds. Ie, you can glue strips of it on to fiberglass or aluminum hulls.

 

[nimblemotors]

Supposedly 3M's DP-8005 will achieve full strength UHMW-PE bonds. Ie, you can glue strips of it on to fiberglass or aluminum hulls.

Excellent, very useful, but on a bigger scale, the glue costs 10x more than the UHMW !!

 

[ImaginaryNumber]

...Aluminum oxide isn't the best "hardening" filler material you can employ. It's typical use is for as a thermal break and temperature control, not as abrasion resistant filler. Harder materials (aluminum is very soft) are the usual choices. Iron fillings make an excellent choice, though they can rust if exposed. Copper is relatively soft, but much better than aluminum. Bronze and monel dust is good, but costly, as are Kevlar fibers. Sand and stone are cost effective alternatives. Sand is typically sandstone and quartz, both relatively soft compared to decomposed granite and other, more noble stone types.

Another option is mica. I have used it in epoxy, it makes it very hard and abrasion resistant. Some aerospace resins are mica filled. It will destroy a drill bit. I have no experience with it in salt water.

The Mohs scale of hardness is often used for minerals, with Talc at 1 and Diamond at 10.

Mica is relatively soft at 2.8 (roughly the same as copper, aluminum and gold)

Granite is primarily comprised of quartz (7), feldspar (6), and mica (2.8)
Most sandstone is primarily quartz and feldspar
Most inland sand is quartz, with marine sands often calcium carbonate (coral, shells, etc) (3)

Aluminum oxide is just below diamond at 9, and is commonly used for grinding wheels

The foregoing is not a recommendation for an abrasion-resistant hull material, just a clarification on hardness.

http://www.rockrollers.com/features/hardness.html
http://www.reade.com/Particle_Briefings/mohs_hardness_abrasive_grit.html
http://en.wikipedia.org/wiki/Granite
http://en.wikipedia.org/wiki/Sandstone
http://en.wikipedia.org/wiki/Sand

 

[sprit]

I have heard that filling biaxial glass with with a putty made of epoxy resin and fumed silica gives a hard smooth surface. I think that the silica is made from quartz, which the previous post says has a Mohs rating of 7.

Does anyone know how good this surface is for real life abrasion resistance?