opinions re: epoxy vs. plastic hulls, lead vs. iron keels
 

hi

interested if anyone has any opinions on the following:

1. Is there any specific disadvantage, other than price and possibly environmental considerations in manufacturing, of an epoxy hull compared to a poly/vinyl-ester hull? (comparing apples to apples - i.e. assuming both cored with same core material)

2. (I know this has been discussed somewhat previously & have looked at the posts) what disadvantages are there to lead versus iron keels.

i ask just because as i look around for next boatie, it seems to me that apart from (relatively) small price differences, there are no disadvantages to epoxy hull and lead keel. i do see some disadvantages to carbon fiber spars.

would be interested in others' thoughts.

I don't know of any production boat made with epoxy. Cold molded are the most common in custom or home built boats made with epoxy.

hanse (on larger models) & tartan both use epoxy glass construction.

Epoxy is subject to thermal distortion at lower temperatures than poly/vinyester resins, so in the case of most epoxy-composite boats, dark colors are best avoided. However, the will generally be more resistant to osmosis, stronger, and a bit lighter.

Lead is more expensive and more toxic. However, it has a higher density and as such will have less wetted surface area for the same righting moment (weight in ballast). It is also far more forgiving in a collision, with an externally mounted keel, since the lead tends to deform and absorb a lot of the impact energy, rather than transfer it to the keel support structure.


Carbon fiber spars have a few major disadvantages, especially for a cruising boat in remote regions. First, it isn't as easily repaired, requiring fairly sophisticated materials and techniques to repair it. Second, in a lightning strike, a carbon fiber spar may look fine, but actually have serious delaminated areas and be a serious danger to the boat. Third, there are some serious galvanic corrosion issues with hardware attachment to a carbon fiber spar, given carbon fiber (graphite) relatively high position on the anodic scale.

thanks for the replies - much appreciated - perhaps i wasnt totally clear, i am reasonably familiar with the advantages of epoxy hulls/lead keels (and disadvantages of carbon fiber spars), however, i'm looking for any disadvantages of these (apart from, as i mentioned, cost), in anyone's opininions.

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?

Well...there is a great deal of difficulty apparently in building a composite epoxy hull and there have been admitted failures. If you read the "Tartan Buyers Pls Note" thread under Buying a boat forums you will see several owners with big time problems and a series of interview links with designer TimJackett that detail some of the issues that had to be worked out...sometimes in production...with the construction techniques and bonding issues. Both Tartan and C&C boats are built using the same technology. I believe the thermal distortion issues around dark hulls Dawg mentions can be solved with outer mat layers of vinylester. The Jackett interviews cover this issue and I think you will find them interesting. Just remember they are the company's views and there are at least two lawsuits currently filed and a number of folks who disagree quite vehemently with Jackett's dismissiveness of some of the issues.
I can't think of any disadvantages to lead keels.
One additional disadvantage of carbon fiber masts is that many insurance companies will insure the boat but not the mast. A guy here a month or two ago lost his due to a lightning strike and insurance excluded it and he had a big bill.

My cousin lost a very expensive carbon fiber mast to a lightning strike a week after he put it in. He has good insurance so he just went and got another. But the thing was a total loss - He was lucky he wasnt on the way to Bermuda when it happened.

Epoxy, lead & carbon
 

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.

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.

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.

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.

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.

I would say that Tartan still has some serious issues to work out with their Epoxy-based laminates at the moment.

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.

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.

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. :rolleyes::rolleyes:

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.

Carlsbad...suggest you read the "prospective Tartan buyers thread" before you dismiss those of us who think there is more than clinging to old technology going on when we choose NOT to embrace epoxy.

As to carbon fiber masts...you are correct that the are no more likely to be hit by lightning than aluminum. On aluminum boats you are unlikely to need a mast replacement due to a strike since the rig usually stays up. If a carbon mast is damaged, you have to replace the whole thing. If you are a cruiser outside of the US...just try getting any work done in the Caribe or Mexico for example...whereas someone can always fix an aluminum mast.
Carbon has a lot of performance advantages and can eliminate the need for shrouds and chain plates and other conventional rig complications...so there is a place for it in the market but cruisers should be aware of the disadvantages as well as the advantages. I stand by my insurance issue...the guy with the Freedom here a couple of weeks ago specifically had the carbon mast excluded from coverage. This is not to say that others will not insure one...but you may be paying a premium for that coverage.

BTW...if cost is the only issue with Epoxy...why are MORE costly brands such as Hinckley, Oyster etc. not using it already? Hinckley is doing some carbon masts but chooses NOT to use epoxy.