How to evaluate self designed and built boat

[workmaster2n]

We have had our current boat for 2 years and realize she just doesn't have the performance we'd like in order to do the types of trips we want. I've sailed on a couple performance catamarans and just enjoy that type of sailing a lot more than what my current boat offers.

I live in Australia, and the price of used boats, especially catamarans, is absolutely mind boggling right now. It's only 10% more to buy a brand new boat.

The other day, I saw a very sleek looking catamaran in my marina with a for sale sign. Finally got a hold of the owner and took a look around. From what I can see, it looks to be a decent boat.

The owner is the builder of the boat. He was a professional boat builder by trade and built this for himself after "thinking what I would want in a boat." She's strip plank cedar with glass inside and out. The quality of the work seems to be pretty decent, and the boat has been floating for 20 years, so there's no obviously noticeable defects.

I understand that I can have a surveyor who specializes in cedar boats take a look at the boat to spot potential water ingress or other structural issues, but is there any way to get some rough technical numbers of the boat? Would it be possible to figure out load carrying capacity or drag coefficients? The boat hasn't been sailed in 10 years, so although the owner lives aboard and occasionally cleans the bottom, there's gonna be a non zero amount of growth. I can of course ask to go on a test sail in moderate or light winds to see how she handles, but I'm not sure what one isolated day will tell us.

With a production boat you get polars (however inflated) and other owners who can give you an idea of performance. I'm trying to think of a way to do something similar with a boat that has no designs and is a one off build. My fear is getting a boat that looks like it should be fast, but turns out to be dreadfully slow.

[boatpoker]

Pay a qualified naval architect with cat experience to review the blueprints and designed construction methods.

[workmaster2n]

Originally Posted by boatpoker

review the blueprints and designed construction methods.

I'll ask if there are blueprints still around, but if they have been lost/never existed, is there anything that can be done?

[boatpoker]

Originally Posted by workmaster2n

I'll ask if there are blueprints still around, but if they have been lost/never existed, is there anything that can be done?

Be pretty expensive to hire and NA to measure, examine and write a report. Nor sure it's worth it if all you want is a list of numbers. A full day sea trial in brisk weather will tell you much more anyway.

Definitely look for a an old wood boat surveyor with impeccable credentials.
Vet all the credentials, there are a lot of surveyors out there with hyped or fake credentials. Choosing a Marine Surveyor & 10 questions to ask

[Chotu]

Originally Posted by workmaster2n

I'll ask if there are blueprints still around, but if they have been lost/never existed, is there anything that can be done?

There should be a set of plans somewhere. He had to have had measurements to build the thing in the first place.

But yes there is certainly something you can do.

You can take the measurements of the boat and compare it to other boats.

It won’t be easy, but you can take measurements at certain points all the way down the hall. Inside the boat. You can create a set of measurements at even intervals. Those are call “stations” in the plans. When it comes out of the water, you can then measure the depth/circumference of the hull at each station.

Based on the amount of boat below the waterline, you’ll know the displacement. You can also find the prismatic coefficient this way as well.

Next, measure out the sail area. Tally that up.

The displacement, the fineness of the hulls and the sail area can then all be compared to other boats of similar length to see how much performance you’ll get.

If it has boards and narrow hulls, you’re probably onto a performance boat.

It’s probably definitely a full day’s work and then another day to do all the math and make sure everything is correct, comparing it to other boats.

[boatpoker]

Originally Posted by Chotu

There should be a set of plans somewhere. He had to have had measurements to build the thing in the first place.

But yes there is certainly something you can do.

You can take the measurements of the boat and compare it to other boats.

It won’t be easy, but you can take measurements at certain points all the way down the hall. Inside the boat. You can create a set of measurements at even intervals. Those are call “stations” in the plans. When it comes out of the water, you can then measure the depth/circumference of the hull at each station.

Based on the amount of boat below the waterline, you’ll know the displacement. You can also find the prismatic coefficient this way as well.

Next, measure out the sail area. Tally that up.

The displacement, the fineness of the hulls and the sail area can then all be compared to other boats of similar length to see how much performance you’ll get.

If it has boards and narrow hulls, you’re probably onto a performance boat.

It’s probably definitely a full day’s work and then another day to do all the math and make sure everything is correct, comparing it to other boats.

I doubt someone untrained would be proficient in measuring the 8 stations using Simpsons rule number 3 and coming up with an accurate tonnage block coefficient ... and if he did he would have no idea what it meant. Nor would he have anything to compare it to as I've never seen a manufacturer publish those numbers.

[Fore and Aft]

workmaster2n there's lots of factors involved with a boat's performance. You say the cat has not been sailed in 10 years, so I bet the sails are all old and going to do nothing to help the cat sail well. So, then you have to think how much you are willing to invest in a good set of sails. ($20,000 is not unrealistic for a good fully battened square top mainsail) Since the cats been sitting around so long what is the antifoul build up like? You might have a bottom like a golf ball. Then how much gear is onboard and how much do you want to load her up? If you're thinking air conditioning, generator, spares for everything including a full rebuild engine kit then it's starting to add up. Then you have to look at your own sailing ability. (You purchased a Simpson Cloud 12 cat so I can guess you are no Russell Coutts). I would hazard a guess to say as long as the cat design hulls have a good beam length ratio, reasonable bridge deck clearance and she has not been overbuilt then there is a potential for her to perform well provided you don't overload her, and you know how to tweak the sails for maximum drive.
Cheers

[Chotu]

Originally Posted by boatpoker

I doubt someone untrained would be proficient in measuring the 8 stations using Simpsons rule number 3 and coming up with an accurate tonnage block coefficient ... and if he did he would have no idea what it meant. Nor would he have anything to compare it to as I've never seen a manufacturer publish those numbers.

Well, true. maybe not. But that is the only way to get what he’s asking for if absolutely no information is available on the boat

I mean he doesn’t need to do the prismatic coefficient. I think I went a little overboard. But he can figure out the displacement. Take a look at the fineness of the hulls.. Take a look at the sail area. Compare it to other boats of similar size. Check for keels or dagger boards.

That would go a pretty long way to evaluating performance.

A real rough and dirty way would be to see the boat out of the water, and see other catamarans of similar size out of the water somewhere nearby, and just look visually and see how much bottom paint there is versus the others. Then just check sail area.

To make it really simple, you could just say, how much boat is below the water? Compare that to other boats nearby of similar size, ones where he knows the performance, and he’s got a pretty good estimation.

Less boat below the water is faster assuming same sail area.

[workmaster2n]

Originally Posted by Fore and Aft

So, then you have to think how much you are willing to invest.

Completely agree with this. I know the boat needs $200k worth of sails, rigging, and equipment to make her into a modern cruiser. She's not a project boat, but she also isn't step on and sail off. It's just that given the current market and my current sailing plans, I don't see another boat coming onto the market with similar theoretical capabilities for even 30% more money.

I also like taking on small projects, and this boat has quite a few for me to tackle. So there's an element of enjoying the process of getting her ready as well as actually using her once she's "done".

I had to look up who Russell Coutts was, so, yep, definitely not him The Simpson was our first boat and we've learned so much on her. Now it's time to take those lessons onto the next one!

[workmaster2n]

Originally Posted by boatpoker

A full day sea trial in brisk weather will tell you much more anyway.

I think this will have to be the go to. The owner seems amicable to taking the boat out, so hopefully won't be too bothered with a long day out to see how the boat performs.

[Fore and Aft]

workmaster2n I once made Russell a cup of tea when he popped into our workshop in Wellington for a yarn with my boss. The trouble with a custom design is that the $200k you invest is probably never going to help the cat's resale value. Not to mention the fact she is 20 years old already. Have you looked overseas for a performance cat that you could buy and import to Australia. Or what about approaching a few multihull brokers to see if he knows off anything coming on the market soon. You would be surprised how many boats sell without them even being advertised.
Cheers

[JPA Cate]

A lot of people will warn you off buying a "home built" boat. If the current owner is the builder, he may have all the drawings, too, and they will be of use to you. If he was/is a "good" boat builder, everything shall have been done right. He's not the only boat builder in Oz and a number of them would build a boat for their own use, with intention to sail it for a year or so (neatly de-bugging them, if there were problems), then sell them. Some of those boats are super buys, because "nobody" knows about them except other boat builders! If the boat was built with epoxy and f/glass, termites can't chew into it. This is handy to be able to tell AQIS, when you're returning from New Caledonia, for instance. I don't know about vinylester. All the information you can get from the drawings will help with the insurance picture. Find out if the owner can transfer his policy to you.

Actually, if the boat is not now insured, be aware you won't be able to take it to a boatyard without insurance, so continuing the policy under your own name is important, or at least start talking to potential insurers and compare policies.. A new insurance company may want it surveyed, and they can point you to surveyors in your area.

I hope she turns out to be a real gem.

Good luck with it all.

Ann

[workmaster2n]

Originally Posted by Fore and Aft

the $200k you invest is probably never going to help the cat's resale value.

I'm 100% onboard with this. Resale is a consideration, but I'm fortunate that it doesn't need to be a driving consideration for me. But it is definitely good to keep in mind.

Originally Posted by Fore and Aft

Have you looked overseas for a performance cat that you could buy and import to Australia.

Yep - been keeping an eye on all of APAC. The problem I ran into is you'll need to put down a couple grand to go see the boat yourself plus flying out a surveyor. Then import into Australia is ~15% boat price. Add in ~40-60k for delivery and you'd need a pretty heavy discount to make it worth it. That's not to say those boats don't exist, I just haven't had luck with them.

Originally Posted by Fore and Aft

Or what about approaching a few multihull brokers to see if he knows off anything coming on the market soon. You would be surprised how many boats sell without them even being advertised.
Cheers

I've done my best to contact every broker with a reasonable sized fleet (I'm sure I've missed some lone wolf brokers who operate out of their homes). Get the occasional message from the brokers, but usually it's to announce another price drop on a still overpriced boat.

I really do appreciate your ideas. They are excellent starting points.

[workmaster2n]

Originally Posted by JPA Cate

Actually, if the boat is not now insured, be aware you won't be able to take it to a boatyard without insurance, so continuing the policy under your own name is important, or at least start talking to potential insurers and compare policies.. A new insurance company may want it surveyed, and they can point you to surveyors in your area.

I hope she turns out to be a real gem.

Good luck with it all.

Ann

That's a great point about insurance! The boat is currently not insured. Fortunately, there are a couple beaches near us where cats can be safely grounded, so that's where we'll head for a survey. My purchasing survey on my current vessel counted for my current insurance policy, but good call to check if the same rules would apply for this boat.

I appreciate what you've said about boat builder's boats. I agree that there is the potential for a gem to be sitting in front of our eyes, it's just hidden beneath a bit of dust.

[Jim Cate]

I appreciate what you've said about boat builder's boats. I agree that there is the potential for a gem to be sitting in front of our eyes, it's just hidden beneath a bit of dust.

What Ann didn't mention is that we have owned and sailed a one-off strip planked monohull for 23 years now. She was built by a master shipwright and his wife for their own use, and was intended as a sort of floating advertisement for his business. We had Jon Sayer, the designer, on board early on and he said "you just couldn't afford to pay someone to build to this quality". We have felt fortunate to be her stewards for all these years.

We've lived aboard full time and covered around 70,000 miles in her during those years and never had any regrets about our choice of a "home built one-off timber boat" that all the pundits (who don't have one) say to avoid at all costs!

Jim