Aluminum Semi-Displacement Catamaran Build

[Bkay]

Yes, the design and style is very functional and the guys swear I can do pull ups on it (they also serve as a wire chase). It's really just a few areas of poor fit that should have been corrected but the guys working on it seem to have been pulled off for something else. Now they have the lattitude to go back and clean up some details that they weren't happy with.

Like everyone else, I'm concerned about what's happening and knowing they will have to stop work if they can't work safely. I'm not holding my breath on completion...I've been fooled too many times already.

Good luck to you and your family!

 

[Bkay]

This is such an interesting, specialized design, and a great account of building an aluminum cat. Looking forward to the finish line, as I suspect Bkay is!

Yup. Its definitely taken a few years off my life. But as the old saying goes, that which does not kill us still really sucks!

 

[Bkay]

Because of some previous construction hiccups I have not posted a lot of progress photos. But the new guys who are getting me across the finish line are doing a bang-up job so I want to give them a little good press.

They dropped her in the water yesterday to mark waterline and see if she floated right side up. All looked good, welds were solid, and the water stayed on the outside. After a little trim ballast, bottom paint, and some more detail work she goes back in for sea trials.

 

[boathealer]

Oh, My! That's just AWESOME!

 

[cardude01]

Dude, so excited for you!

What’s the beam?

 

[Blissboat]

Looks terrific, Bkay. As I joined this thread only recently, I have to ask what yard is doing your build?

 

[Bkay]

What’s the beam?

It's 14 feet. The NA who designed the boat, Scott Jutson, did good work. I knew about what I wanted, although I suspect he would have recommended more beam. But once I measured my slip and said "38 x 14 feet" he went to work designing everything around that.

That's one big advantage to working with an NA and in Aluminum (or steel or wood). They are all one off boats so you can tweak and stretch things within the limits of physics and budget.

 

[Bkay]

I have to ask what yard is doing your build?

My contract is with Waterline Systems, but I think they are going to be doing their commercial construction under the name US Watercraft.

 

[Genecop]

Wow, congrats, happy for you....

 

[Larmex99]

While waiting for Bkay to post sea trial results I am posting progress pics of my 42x16 cat project. The builder just got approval to begin manufacturing again after a 6 week hiatus.
Lots left to do but they are scheduling completion for the first week of August. We shall see.

 

[Bkay]

Larmex, im happy to hear that. I hope all is going well in isolation and you've been able to get home!

Sorry I have not posted. I'm doing this on my phone and my thumb typing is not so hot. In short, my sea trials went very well. The NA nailed running gear specs and engine loading was spot on, she floated on her lines (with a little trim ballast) and speed was better than expected. I'll have to post the details later.

I'm down this weekend for final inspection. Boat was supposed to be in the water and I was supposed to stay aboard tonight. But they are still cleaning up before launch. Hopefully we go over tomorrow.

Hmmm...tried to upload some pics from my phone, but no joy. Ill try again tomorrow from another computer.

Thanks LARMEX for waking me up and congrats on your project!

 

[Larmex99]

Bkay,
You are my inspiration. Keep the info flowing. Enjoy your well earned results!
Larmex99

 

[cardude01]

Larmex, im happy to hear that. I hope all is going well in isolation and you've been able to get home!



Sorry I have not posted. I'm doing this on my phone and my thumb typing is not so hot. In short, my sea trials went very well. The NA nailed running gear specs and engine loading was spot on, she floated on her lines (with a little trim ballast) and speed was better than expected. I'll have to post the details later.



I'm down this weekend for final inspection. Boat was supposed to be in the water and I was supposed to stay aboard tonight. But they are still cleaning up before launch. Hopefully we go over tomorrow.



Hmmm...tried to upload some pics from my phone, but no joy. Ill try again tomorrow from another computer.



Thanks LARMEX for waking me up and congrats on your project!

Fantastic news! Can’t wait for the pics. Maybe a video? Although to post videos you first have to upload to YouTube or wherever, so a bit of a PITA.

 

[Bkay]

Alright, let me try on a slightly bigger phone...

If this works I'll post an update. If it doesn't work, I guess no one will see this comment.

 

[KnotYet]

Looking very good!

 

[VirtualHuck]

Just wow!

 

[Bkay]

Hey, what do you know, it worked! So in short, sea trials went well. James River Equipment, our John Deere dealer, was very squared away. They were involved with the installation and they nailed it. The sales rep was not at all surprised, but the rest of us were.

The NA also nailed it. He provided the prop specs and they were right on. You assume the builder followed the NA's specifications during construction, but that's not always a good assumption. So I was pleased we were about on our lines, trim ballast to be expected. We didn't have to make any adjustments to the prop and once we get the ballast properly located I think we'll be fine. Now, having said that, I have not run the boat in adverse conditions.

The boat ran smooth! I hoped for a quiet running boat, but I was mentally prepared for typical aluminum noise and vibration and at one point I discovered a problem with the original builder and the construction of the running gear. They corrected it, but we had to compromise on propeller tip clearance - so I was nervous I'd be driving a box of rocks. The NA got involved and said he was comfortable with the compromise and it turns out the boat was as quiet as I hoped. JD technician said it was the quietest aluminum boat he's been on. My surveyor said "that's not too bad", which may be the nicest thing he's ever said (kidding, hes a good guy, but he's spring loaded in the "no" position).

The builders finishing the boat did a good job. A boat like this is not in their wheelhouse. They do hard core working boats and outsourced some of the detail work (some wood work and flooring). The best thing I can say about these guys is I trusted they wanted to do the right thing, get the boat done to customer expectations, they were honest, and they can produce solid commercial boats! I haven't been able to say that about everyone involved in the early days of the project.

I dont have performance numbers. But when I get them from JD, or create my own with an actual cruising load on board, I'll post them. But right now I'm having a beer!

 

[Bkay]

In case you doubted my beer comment!

 

[Larmex99]

Looks great! Can’t wait for the performance specs and more pics.

 

[Bkay]

The unofficial numbers were 18.1 knots at 2300 rpm and 74 db (with doors cracked so techs could wire to the engines). I didn't get fuel burn numbers, the JD guys said they would compile a report and send it to me. We did multiple runs and they will provide each run and the averages.

 

[Larmex99]

So, you have the M1 rated 4045? That is pretty good speed for 160 HP in a boat that size.

 

[Blissboat]

Congrats, Bkay! It's definitely Miller time for you. What a cool project.

 

[Miz Trom]

Congratulations!

Hi Bkay:

I have immensely enjoyed your build thread. The photos and descriptions are awesome!

I understand completely your reticence when it came to discussing your problems with the original builder. We went through a similar situation, and your restraint has been admirable.

However, what I admire most about your process (and wished we had done), is that you hired the NA first, then took the plans to a builder. That was very smart.

I love her looks and in particular, the 14-ft beam. She is unpretentious and very salty-looking. Do say, what is her name?

Cheers and stay safe,
Mrs. Trombley

 

[Bkay]

However, what I admire most about your process (and wished we had done), is that you hired the NA first, then took the plans to a builder. That was very smart.

... Do say, what is her name?

Technically the builder engaged the NA, but I made sure the contract with the NA was a done deal before I contracted with the builder. I didn't want to get caught between an NA working for me and a builder also working for me. It seems easy to have them blame each other for faults. My theory was this way the builder is responsible regardless of where the problem originated. Of course, that assumes the builder stays with the project until completion. I was familiar with the NA and had been on similar boats before. So that gave me some comfort that he was a skilled professional and this was not a totally unique concept.

Oh, and here's her name painted on...

 

[Bkay]

Just kidding...my wife didn't find that amusing either. Her name is WINGSPAN.

 

[Larmex99]

A few new pics from my build. Frames are almost completed and the house will be flipped shortly. At least it is beginning to look somewhat like a boat.

 

[O C Diver]

Bkay, your fuel consumption numbers should be displayable on the square screen in real time. Go into the manual and select it as one of the displayed options.



I have it in the lower right corner reading 2.0 gallons per hour. It seems to be quite accurate as the computer makes the calculation between injection rate and RPM.

Ted

 

[cardude01]

Bkay, your fuel consumption numbers should be displayable on the square screen in real time. Go into the manual and select it as one of the displayed options.



View attachment 102619



I have it in the lower right corner reading 2.0 gallons per hour. It seems to be quite accurate as the computer makes the calculation between injection rate and RPM.



Ted

At 2gph what speed does that usually get you, with no current? That’s an impressively low fuel burn for a big boat like yours.

I’m cruising at 2000 rpm now with the jib up and about 17 knots of wind on the beam, and making 6.7 knots. At 2000 rpm my Yanmar 4JH4-hte burns a little over 1gph. But my boat is pretty small, and without the sail I’d lose about .25-.50 knot of speed.

 

[O C Diver]

At 2gph what speed does that usually get you, with no current? That’s an impressively low fuel burn for a big boat like yours.

I’m cruising at 2000 rpm now with the jib up and about 17 knots of wind on the beam, and making 6.7 knots. At 2000 rpm my Yanmar 4JH4-hte burns a little over 1gph. But my boat is pretty small, and without the sail I’d lose about .25-.50 knot of speed.

2 GPH gives me 7 knots before adding or subtracting current and wind. Full fuel and water costs 1 or 2 tenths of a knot.

Ted

 

[cardude01]

Wow. 7 knots at 2gph is really impressive for that big boat.