Interesting. While selene seems to command a high price in teh used market, your rating is only 5, while you have Seahorse rated at 8, but commands a much lower price on eh used market (even for fiberglass hulls).
I think based on other comments and information I didn't know at the time, I rated Seahorse too high. I still think of Selene as being a good, solid boat, but a step below some others. Still I wouldn't have been uncomfortable rating them a 6.
My ratings for Seahorse were only based on steel hulls and really based on Diesel Duck and Coot. I'm only aware of the one incident pointed out here, but even based on that I'd lower them to a 6 or 7 perhaps.
The lower price doesn't surprise me at all on the used market. First, they're priced fairly low when new. Then people just don't want steel in that size boat, so they've got a limited market.
The quality of most boats is good. There are very few boats built that you need to worry about delamination or other major problems. The biggest differences are design (including sea states designed for), quality of equipment and installation of equipment, and then things like tendency to leak in various areas whether from above or outside.
Boats have been around long enough that you don't see bad hulls, bad designs in that respect. You may see someone purchasing a boat designed for coastal cruising and disappointed it's not build for ocean going.
Quality of equipment, most use the same of fairly equal suppliers. However, they may shortcut on things like hoses and tanks. They may also do it on teak and other woods, going thinner than desired. Some build interiors that perhaps we wouldn't like at all but I see that as just an issue of taste, not quality. Now, back on installation of equipment, I'll give a couple of examples where that comes into play. I do not like Nordhavn's commissioning system. It takes way too long and seems to be fraught with potential issues. I see buyers taking the entire first year getting it all properly sorted. I would probably raise my Sea Ray number slightly. I like Sea Ray. However, I've seen buyers of their L series with punch lists and post purchase issues that are just way too long. We were a potential buyer until uncovering those issues. That doesn't impact the tried and true Sundancer series, but might or might not impact some of the new models, such as the fly versions.
Not on the list, but a boat that gets more discussion as to quality than any I know is Azimut. A lot of haters. Confusing. European buyers are very happy. US buyers are driven insane by things like wiring of the electronics and it appears to be on some boats built in Italy and some from Brazil. Yes, Azumut builds in Brazil for this market too. However, their hull is fine. Part of the US issue is that all warranty is handled through Marine Max. They act as the dealer and the manufacturer's representative, and people struggle to get all the issues fixed. I'd give them a "don't touch" score in the US but that basic boat is fine.
In many ways, we're not just rating quality of build, but quality of the total experience. There's one boat that many owners really like but if you put it on the list, it would get a zero from me in terms of buying it new because I just don't trust them. On the other hand, a used one can be surveyed and it is what it is, but you're not putting money at risk for a long build period.
It's interesting too to see things that influence our ratings. Richard's trips on Dauntless have to impact how one views KK. All those cruising the world on Nordhavn surely influences opinion, although the Atlantic Crossing they did lowered my opinion of them. Probably why they haven't repeated. Part of it is size as those cruising the world are most often 60' and above and the ones on the Crossing were largely smaller, but also Nordhavn was having issues at that time with stabilizers. Reading Tony Fleming's cruise blogs certainly impacts how I feel about Fleming.
I am not familiar with most brands, but i will post my limited opinion as well.
