SailNet Community - View Single Post - opinions re: epoxy vs. plastic hulls, lead vs. iron keels
View Single Post
  #9  
Old 08-06-2008
sailingdog's Avatar
sailingdog sailingdog is offline
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Quote:
i was not aware of the issue of thermal distortion and dark colours, though - interesting - how does that work? if this is true, why do so many tartans have dark hull colours?
Most tartans, until just recently, were standard polyester/vinylester construction, so the thermal deformation wasn't an issue. Cam does mention one possible work around, which is to use several layers of polyester or vinylester resin as a finish coat, but that doesn't always work.

Quote:
Originally Posted by Carlsbad View Post
As an industrial engineer who has worked with advanced materials for many years, I am continuously amazed at how people cling to old technology in the face of overwhelming evidence supporting newer materials. At the outset, I should point out that I own an older Tartan 3500 that does not incorporate the newer technologies (the newer Tartans do) that I mention below. Looking forward to buying a new boat, I've spent a good deal of time investigating these materials choices.

Epoxy resins unquestionably produce a much stronger, lighter and stiffer laminate. The ONLY reason that most sailboat manufacturers continue to use polyester resins is that they cost a fraction of epoxy resins. Epoxy is far more environmentally friendly since it produces no styrenes. Although far more costly to use in the manufacturing process, epoxy resins result in a far superior structural product. Tartan pioneered the use of these resins in their products 6-7 years ago. Others are now starting to follow; Hanse provides an option for epoxy in its larger boats at a considerably higher price. The only reason that manufacturers continue to use polyester resins is COST.
I would say that Tartan still has some serious issues to work out with their Epoxy-based laminates at the moment.

Quote:
Lead is unquestionably the best choice in materials for keels due to its much higher density, which dramatically influences the designed righting moment. The builders that use iron keels do so soley to save money. The compromise is found in a lesser rig design to accommodate the inferior righting moment. Lead keels also have a much longer life than iron by reason of the corrosion characteristics of iron. Again, the only reason that some builders use iron keels is COST.
If density was really the primary characteristic for a good keel material, they'd be using Osmium or Iridium, either of which has almost twice the density of Lead. Lead is 11.34 g/cc, where Osmium is 22.6 g/cc or thereabouts. Osmium is also fairly toxic, and the Osmium tetraoxide compounds are lethal... Lead is the best reasonably priced material for keels, and its relative malleability can also help protect the boat in the case of a hard grounding—since lead will often deform and absorb much of the energy in a hard grounding, rather than transmitting the force directly to the keel-hull join.

Quote:
Carbon spars are FAR superior to aluminum. They are less than half the weight of aluminum, and are stronger as well. Racing sailors are well familiar with the performance advantages of carbon spars. But as a cruising sailor, the advantages are very apparent as well; less weight aloft produces a much better sailing motion and an easier rig to manage. The suggestion that carbon masts are more susceptible to lightning damage is simply not supported by any facts. Additionally, boats with carbon rigs are fully insurable by all major marine insurers. Again, the only reason that most manufacturers use alloy spars is for reasons of COST.
Actually, they are far more susceptible to difficult to diagnose lightning related damage, since the surface may appear fine, but the interior of the laminate could be damaged and delaminating with little or no warning of the impending failure.

Quote:
Most quality sailboat manufacturers have plans to incorporate epoxy resins in their laminates, and provide carbon spars as standard materials. Only considerations of cost keep them from getting there. Tartan go there years ago by investing in advanced materials technologies, and now lead the pack.
This is a really bad blanket statement... as many manufacturers have no plans to use epoxy due to cost and no reason to go to carbon fiber spars due to cost and manufacturing complexity. Tartan isn't really there yet—since they're having serious manufacturing defects with their epoxy-resin boats... I'd say they're still a work in progress.

Given Tartan's recent track record, and how they've basically screwed a lot of the more recent buyers of the marque.... I am surprised to see a Tartan owner defending the brand ATM.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.

Last edited by sailingdog; 08-06-2008 at 11:03 AM.
Reply With Quote Share with Facebook