Re: is this worth anything???
I had a 1971 Duo Trihull, the model was a Gypsy. Mine was blue with a Mercruiser 120hp Stern Drive. I had bought a few of those for parts while fixing up mine, I cut up one after selling the other, the hull had been in an accident on the road and had some serious damage in the bow area. They did have wood stringers and a wood transom, but those hulls were made from laminated glass over foam. the lower hull was almost an inch thick, and the entire hull was made up of an outer layer of glass, then about 5/8" of foam, then an inner layer of woven glass. It was probably the most overbuilt trihull I ever saw. It was heavy but they were made to take something like 135hp or so. Mine did about 34mph with the I/O set up, a buddy had one that looked like yours with a 100 hp Mercury outboard that did over 40 mph in light chop. They are a decent ride as trihulls go, they will pound in rough water and over wakes but I can't see you every hurting the hull after seeing how those were built.
Duo was at one time it's own company that sort of branched off of Thunderbird speed boats, in or around 1966, they were bought out by Starcraft and sold as a high end line. They were a faster hull than the Starcraft boats and ran better on plane, but were heavier.
I would in no way compare them to a Bayliner today, they were very well built and at the top of their price range back then. The original bill of sale and dealers receipt which I had for my 1971 Duo Gypsy was $5671,with a painted TeeNee trailer, which was about the price of a Corvette or well dressed Cadillac then. They were more than 30% more expensive than say a Starcraft or MFG of the same vintage.
I have to say that I've not seen very many Duo boats, the most sought after models are their V hulls but the name itself isn't seen very often these days. I don't think they made them in the huge numbers, I don't think I've seen more than a dozen of these over the past 4 or 5 years, yours included.
I've owned several trihulls, with the Starcraft and Duo versions being my favorites overall. I'd put MFG and Chrysler a close third and forth, but some older trihull designs were downright harsh. The Duo had a more unique hull design which rode with the outer hulls clear of the water on plane. The Starcraft had a bit more freeboard and was a good bit lighter but the Duo felt like a whole lot more boat underneath you. Both were rock solid at rest which made them great fishing boats.
As far as value, I don't think any trihull brings a premium, I think the above estimate is about right, $500 to $1500 depending on condition and time of the year.
With the economy the way it is, I'd lean towards the lower end of that estimate. The motor alone probably has more value than the boat itself if it's healthy.