I’ve just noticed a lot of new LOB booking engines lately.
That's the one quantitative thing you can ascertain.
Scuba Board attracts commercial posts like that, a few actually using their corporate names in the sig lines, some lurking beneath the guise of friendly advice. You've gotten 7 replies so far, you couldn't ask for a better list of SB repliers. I am a highly opinionated curmudgeon, but I am the only poster from Illinois here that isn't also secretly selling a product...similar to the one you mention.
It's also the best business model possible- you're selling something that somebody else owns. You spend minimal money on a website or ad, look as much as you can as the real official boat ownership (with fine print disclaimers), take the money, do a "pass through" while withholding your 15%. Any nit-wit can do that, in fact, many are. Some innocent and honest, others not so much. They all are at the mercy of the LOB ownership and their product as she is presented on that future date of sailing.
This is the main source for all the pop up banner ads that you're seeing here.
To the other possible topic? The increase in numbers of LOB offerings?
I'm thinking that the heyday was the early 90's, but that's kind of irrelevant as we're seeing more targeted advertising. You're likely seeing a resurgence now for several economic driven reasons.
1) Larger pleasure boats and correctly sized (for diving LOB) are coming on the market for what I'm being told are reasonable pricing. Still requiring monthly payments, now unused boats, they can look like cheap floating hotels.
2) LOB corporations do "flag" privately owned vessels, but now that these corporations have gained foundation, they are quite interested in retaining more financial interest in their offered vessels. (Note: their lawyers counsel against "ownership" per-se) You are seeing expansion driven by the economy of larger scale. Look at the historical McDonalds model.
Remember well that they operate tied to a fixed cost model. A full ship is about the same operational cost as 1/2 full. Like a hotel, unsold rooms are a perishable commodity. You think there's some leeway in pricing to secondary sellers? Could be attractive.
3) Who is buying trips? DEMA barely talks about what very little they know about land based travelers, so there's really not much out there unless you talk with guys the likes of Frank Watson or (the afore referenced) John Dixon, et al. They have long pondered "How do you make $50k in the LOB industry? First, ask your bank for $10m...." I am a self admitted minnow, unable to think like a whale, so I'll defer to those still silent owners.
If you believe general travel industry reportage, it is saying that higher end offerings are doing better overall. (We can discuss actual vs perceived benefit in another thread) I would think that LOB users believe they are getting better value.
As was mentioned above, divers have changed- they are not as adventurous and have become more "perceived risk" adverse. What is better than a micro-cruise ship, replete with attractive staff, no scary locals, and no bugs. It's very attractive in a sanitized way.
Diving has only gotten more expensive, travel has also. It is no longer working pickup trucks in LDS parking lots, it is FedEx guys walking up SUV cluttered driveways delivering packages from on line dive gear vendors. The audience is winnowing down, smart money is following what money there is. Hardware and travel, same same.
We do know that people are spending their money on "experiences". Diving alone is bragging rights while you're back home, much less if you tell them it was onboard a boat like the Calypso. Plus you get to buy the official polo shirt...remember, dive resorts only have t-shirts.
5) Marketing angles: There is much interest in the desire for the "best reefs/coral/fish" and this is tied (incorrectly or not) to "diver impact". LOBs offer the easy argument that they will avoid that...again, truth or perception is irrelevant. It sells.
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I have seen a number of LOBs come and go, starting with the Isla Mia. I have seen over priced LOBs succeed where equally good and way cheaper land based would do just fine. Some great LOB options failed because of impossible travel connections.
As long as there are dreamers with lots of money...or more likely- other people's money...the industry will be there.