Custom 19' all weather, minimalist, strip plank composite 'go fast'

Finally put her in the water for three days and put her through some paces... I'll put together a short video soon.

Day one: First splash in Seal Beach, California. We ran her from there loaded with 800 lbs of people and cargo about 20 miles up the coast to Redondo as a gale was building in the channel. She carved straight into the chop and ride quality was unexpectedly awesome. Turned around and ran her in a following (excellent) and then frolicked in some beam seas and sloppy boat wakes. Behavior in all that was better than expected and she was more comfortable than any 20' boat any of us had ever been in, certainly better speed without pain in rougher water than a RIB or Whaler would do. Since the new outboard was still in early break-in period we didn't open up the throttle much and did max speed about 26kts. Once we got into the Santa Monica Bay it was flat so we opened her up a little, but gingerly as we had no idea how she'd behave. She wasn't ever squirelly but I actually preferred her in rough water, and I got the feeling that top speed in flat water wasn't going to be much more than 30kts, so she was slower than expected in flat seas but exceeding expectations in messy water and wind. She was also a bit drier than expected--there was a certainly wind mist and we were in wetsuits but she never once took on significant green water.

BUT... her downside was, as was somewhat evident in her design--static stability. Even at 2-3 kts she'd instantly self bail and be stable enough to walk on, but stopped... oh boy. With just two men, she would certainly roll quite happily but still felt like a boat. But with three, especially if too many were crowding aft, she become like a narco sub. Unsinkable, unflippable, but 'highly agile'. Ultimate stability is huge because her COG is so low--she would backfill through her open scuppers and we could easily submerge her aft freeboard edge if we misbehaved. She was designed to shrug that off and she did, but to see theory in action was harrowing. To actually downflood into her bilge you have to sink her because of where her vents and clamshells are, but compared to other vessels she is just bonkers in this regard. I was quite proud though that her aft storage lockers stayed bone dry, and tomorrow I'll open her deck hatches and check but through all we did to her I think her bilge stayed completely dry.

Took her out later that night for a lobster dive in the bay, calm water, just two people (total people/cargo 450lbs) and she was quite peaceful and very pleasant in that use.

Day two: I had less time and needed to get some sleep, but I ran her about 25 miles up to Malibu and back with just one small friend so total weight was 300lbs. Water was flat and then we got into a little wind which was fine. Didn't play at all with trim but wide open we went 32kts. She heels to port at that speed but in my experience narrow souped up boats just do that. Trim tabs might help but for a boat with student divers they just get broken off. Lots of dolphins in the water so they rode our bow wave for a while. It occurred to me as this was happening that she made a great 'marine mammal boat' as her minimalism means occupants are inches away from the water and dolphins.

Day three: took her freedive training in the morning with a couple buddies. Again, we crossed that weight threshhold (probably 575lbs of people/cargo) and she was just almost unworkable when static. Once my buddies were in the water though I decided to really work at heeling and overwhelming her so I was hanging off the radar tower, etc, pushing her to some pretty extreme heel and downflood angles until she just wouldn't heel anymore and then letting her snap back to equilibrium when released. I was satisfied that despite all her narco sub tendencies she really does have the ultimate stability she's supposed to have.

There were a few little mechanical kinks--she definitely needs a baffled tank (some free surface effect from the tank may have affected stability) but it's mostly her hull form when loaded heavy. I'd say she mostly does as designed but ended up 350lbs heavier than I anticipated, and heavier especially in her stern since I added the radar tower there after starting/designing her hull, so her operational cargo is much reduced. I went full on 'shoot the channel in any weather then fall out of the boat and dive' but in practice she's more commercially viable if she's more novice friendly. Drain socks would be a simple fix to prevent her from backfilling when abusively loaded and a buoyancy collar would definitely sort her out.

BUT... it did occur to us today that little amas could also sort that out and look sexy. I think if her build quality was less, I'd just slap a buoyancy collar on her and be done but I'm going to do some CAD doodles and research. Small stern amas, in very close that are basically out of the water when she runs *probably* won't affect her running performance (which is excellent) but would settle a little when static and make her incredibly stable. This would certainly make her even more unique.. she's been on my back porch for three years so I'm used to her but her look seems to be quite striking now that she's out in the world. I'd like to keep or even improve that. Gonna sleep on this.

 

I like her long x beam proportions. my last ulight was a 5.5m x 0.9m jonboat intended for river use 6-40hp. Once I accidentally sailed her half the coast of Montenegro with dolphins.
Static stability is a bit bit weak and it's important where you put your feet . Keep weight in the centre of the deck . You use her for diving , some cone tubes at the stern instead of floats ?

 

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Slim tubes , they will not make it difficult to get on board from the water and will not limit planning speed.

 

Yes, weight distro is very important in her current state, definitely that was always in the form but moreso since her stern ended up heavier than anticipated. First few outings on her we were gingerly exploring and playing, this morning I was a little more 'captain' and telling my friends how they should board, etc, and it was better, but she's too close to tolerance when I put more than two people on her. Next time I will not try and model and design so close to the limit of tolerance, but I think she's 'fixable'. In the beginning she wasn't really purpose built as a commercial fast taxi but as I invested more resources into her, and she took shape, I began to feel like she could be a huge draw. And likesaid, she does have spectacular ultimate stability, and my customers are very adventurous but she even to a salty crew she's a bit much.

This is a napkin sketch in CAD but I think this might be the compromise. I'm pretty sure amas need to be very tight to her hull I think or she'll pick up bad running behaviors for our waters (there's a reason why monohulls tend to be favored over catamarans in our sea states), and I mostly want them out of the water when she's moving at speed to reduce drag. The bow built out very light and she runs either level or just slightly bow up at all speeds so far, but I don't want introduce much if any stern lift when she's moving quick. She is built to be boarded port aft using the molded handholds, but those could be continued over the side of the ama. In her current state, she heels so much that's a like just a 6" lift over the side.. again, stupid easy for boarding but mildly buttclenching to anyone already in the vessel since boats are not 'supposed' to do that.

I don't have a ton of experience running small multihulls and they are so much more common as small sailing vessels so I'm not sure if my assumptions are correct... but from what I've gathered and observed very minimal close aft amas would be best for what's really a successfully planing and powered narrow hull with a light bow that already pierces waves nicely. A lot of designs I've seen are also sometimes compromises in the 'ease of construction' department but for her that ship sailed when the first board was laid, and these will need to be sturdy due to her use and speed...

 

What is this design really aiming for? The same stability as a normal boat but with less living space, i.e. more uncomfortable?.
Is a radar needed for the type of navigation that this ship can perform?
I don't understand the why and wherefore of this design. But I must admit that I find it ideal as a decorative object.

 

I didn't notice that side console. That's a bad idea.

I also think that tubes are a better idea than floats that will take away speed on a wave heel.

 

Side console makes the vessel heel to starboard when static, moreso when I'm sitting there. Looks funny. When I designed her I didn't think I'd care about that. But I did that for two reasons--it easier to 'get around' to the bow, and it counterbalances a diver/swimmer hauling in over the port aft boarding edge. The counterbalance thing it does do, moreso if I'm adding my own weight to the saddle seat. The whole 'getting around' thing only works if we're moving at least a few knots because of the form stability issue. I always imagined people moving about the deck at a crouch but everyone wants to stand. Yesterday morning when I decided to be more 'captain' and told my friends to quit standing up and move at a crouch maintaining 3 point contact, static stability improved but again, I think the vessel probably could be more novice friendly.

Yes, I do suspect the amas will create drag in certain trough seas, etc, in which she currently really shines. I don't have experience on a multihulled vessel like I'm now contemplating. I am hoping that I can get more insight on what/how the amas might affect her. Have you personal experience on a motor tri?

I will try to answer your questions, as I have asked myself the same many times over the last three years...
"The same stability as a normal boat with less living space, i.e. more uncomfortable?" -- in a sense, YES. But consider her users (water enthusiasts, many of whom have been on a flavors of 'normal' boats, and some who have not). The minimalism and low freeboard allows her passengers to be closer to the water's surface. I know from a 'normal boat' perspective this is mostly perceived as a design flaw/safety concern. I don't do 'pet the whale' type tours, and am largely indifferent to all the whales, dolphins, sea lions, and seals that frequent my waters, but my customers are less and less frequently jaded ocean hunters and more often just ocean enthusiasts and LOVE to see them and want to have some kind of interaction (these are not my customers but I wanted you to get a visual here):

[As a naval engineer/captain we see a panga style boat demonstrating good ultimate stability during a passenger crowding situation!] This close interaction is not possible on most other 'safer vessels'. Why didn't I just get a panga? Because they're not particularly good when it comes to getting in and out of the water for swimmers/freedivers, particularly novices or anyone not extremely fit. So many of the injuries (and deaths) in my business come from people entering/exiting boats. Windage often plays a role here, and so many 'normal boats' have a lot of windage. Two anchors, giant swim steps, huge ladders [debatable] will help here but that's a larger, slower operation, covering less ground and less conducive to my clientele and business model. I also know there are plenty of purpose built diving and swimming catamarans operating in other waters, but those designs are horrendous in our conditions as a whole.

There is also a little bit of 'love of speed'. When people are closer to the water everything feels faster, and I understand this does not appeal to everyone but 'going fast' can be quite exhilarating to some people for its own sake:

I wanted to capture that feeling in this design; the tiny narrow red inflatables that I've been using for years actually seem to do that fairly well. Besides being on boats, I have spent a good deal of time watching other divers on boats to see what they respond to and enjoy, and I do notice that in some vessels more than others, and I certainly feel it myself. This struck me early on when I started doing 'spearfishing excursions' off the tiny inflatables. I would have a new student, could barely do any diving, but they were absolutely loving the experience of just zooming past the cliffs in a tiny fast boat while wearing a camouflage wetsuit. That aspect of the day was a huge and memorable part of their experience and take away. So then, why not jet-skis? They certainly check the 'go fast' box and offer fairly good fuel economy...? Well, I consider those suicidally bad from a business liability standpoint, kind of obnoxious to have around in the water when we've diving, and, for rougher water (over average afternoon waters) and long runs (I've done 70 miles in a day on one while spearfishing to and from the islands) they get PUNISHING. So, RIBs and little Boston Whalers. With the small RIBs its mostly ride quality. They pound so hard in rough water. Maybe I could have gotten a RIB and installed Shox pedestals for everyone and then I'd be done with it? But, while they offer more of the above 'close interaction' than big boats they offer less than my current design as well as more windage and few hard points. USCG does not permit anyone to sit on the tubes when operating outside of heavily protected waters (harbors, etc), and operationally as a captain who has spent many hundreds of hours on small RIBs I would not permit that on my vessel even if approved by USCG. I'm left with little Boston Whalers. Well, I guess I could've gone that way but when I started this vessel I made out my BOM at $12k, and I really didn't want to mess with retrofitting a molded fiberglass boat, and ride quality in choppy seas in those isn't superb. Again, I guess I could have coughed up the money for four Shox seats but I also had never even sat on one so I didn't know.

"Is a radar needed for the kind of navigation this ship can perform?" -- Yes and no. I'd say 'no' but I also know experienced boaters who would not dream of running after dark, or in the fog, or crossing the Catalina channel (25 miles) without a radar. I felt like that would make her more comfortable for insurance and compliance. Technically USCG would not mandate a radar for a vessel of this size and max speed, but I thought it might help as I intend to use the vessel commercially and not be limited to clear daylight as I my friends and I dive at night in the fog at the islands all the time and don't think it odd or dangerous, and neither do the dive insurers.

"Ideal as a decorative object." -- Well, thank you. That is part of the value and attraction of the vessel. People who know higher end boats and one-offs have commented that she's a 'collector type' boat. Perhaps that's the problem in that I was trying to build a special workboat and she just turned into a collector type one-off? She is very unique and any type of wood core/cold mold type brightwork is not common in my area except on some very large expensive sailing yachts, and never on a powerboat. If she were a 'normal boat' made of fiberglass she would look like all the others in my area. If she were a 'normal boat' design made this way she would stand out and perhaps be highly sellable, but I didn't make her for that for all the above reasons as those boats aren't designed for my specific task and crowd.

 

Here is some rough footage of her on the water for first splash... Some friends were kind enough to come out and drone a bit which is helpful for me to study her wake.