Designing & Building Hammerhead

[OldDan1943]

Originally Posted by Salty Pelican

Thanks Dan! That's where my heart is as well.

Regards, Edwin.

Once you get it built, in the water and sea trials then you can to the additions and fine tuning.

[twistedtree]

Originally Posted by Salty Pelican

Thank you for chiming in, gentlemen.

Here's what I am looking at now:
- Raymarine Quantum 2 doppler radar (great detailing, low power consumption, 20 Nm reach);
- Double VHF;
- Double GPS mushrooms;
- AIS;
- Weather instrument.

I am expecting we'll add a FLIR, but that'll probably sit on the forward rim of the roof on the main room.

For satcom and internet, I am expecting StarLink to be a viable option by the time the ship launches.

Anything I missed?

Regards, Edwin.

Probably one or two Raymarine MFDs? Two would be good from a redundancy perspective, and would normally allow you to spread out the display info.


Auto pilot(s)? I don't think it's widely done elsewhere, but most Nordhavn's, and I'd venture to say 100% of them over 55-60' get outfitted with dual APs.


Increasingly, everything is on N2K, so ask yourself what happens if something takes out the N2K network. It happens. At a minimum, be sure all the junction points are accessible, and know what devices connect where. That way you can trouble shoot efficiently by segmenting/isolating various devices. One trick I learned is that rather than making connections up a mast near a collection of devices, run cables from each device to a convenient, preferably interior location, and have them join the network there. I thanked myself over and over again for doing that.

[twistedtree]

Originally Posted by Salty Pelican

I think the Raymarine M300c would be a great FLIR option. What say you?

https://sensormaritime.com/wp-conten...tasheet-EN.pdf

The M400 is ... offering a bit more, but very, very cost prohibitive. 70-80k vs 7-8k.

Will probably be installed in the mast, just under the radar ...

Regards, Edwin.

I've got an M364 which is one of the M300 family, and probably middle of the range for that family. Right now I've got a real problem with it, and hopefully it will get resolved, but I'm on the third device and they all do the same thing to one degree or another. The camera has PTZ (pan, tilt, zoom), and is stabilized (something they added in this new family which is really nice). However when stabilization is turned on, the camera doesn't stay pointing where you aim it. Out of the box the first camera would tilt to the sky or the deck on it's own, and was completely unusable. With stabilization off, it works fine. FLIR repaired it under warranty saying they found and fixed the problem. But on re-installation, it did exactly the same thing. So they sent me a totally new camera. This one has stable tilt, but the pan drifts. It drifts much more slowly, but over the course of a minute or two it's pointing in a totally different direction. I continue to work with FLIR, and their support has been excellent, but so far we don't have any resolution. So I would hold off for a bit on a stabilized M300 series....

[Salty Pelican]

Thanks for sharing. There'll be two major screens inside and one outside. Relay to the tv in the main room as well as to two additional screens in both main sleeping rooms. That way oversight can be held from various positions.

The LM65h will be fitted with two autopilots (again, Raymarine). One inside, one outside. I think one is electronic the other via ... Oh f*ck, due to Corona too tired to remember basic sh*t. Anyhow, double redundancy.

Regards, Edwin.

[Salty Pelican]

An N2K internal central connection hub is an amazing idea!

Regards, Edwin.

[twistedtree]

Originally Posted by Salty Pelican

An N2K internal central connection hub is an amazing idea!

Regards, Edwin.

Just keep in mind that you have drop cables length limits of 6m, and a cumulative drop cable length limit of something like 70m. You will likely use 6m drops for each mast instrument.

It’s well worth modeling you system with Maretron’s N2KBuilder It’s very tedious, but infinitely better than ending up with a problem. With both a 60’ and 68’ boat, I had to make adjustments to stay within the limits.

[Salty Pelican]

As the LM65h is designed to cruise at relative high speeds, close to its hull speed, there's - with traditional water displacement designs - a design challenge we needed to overcome. As a water displacement design encroaches hull speed, resistance goes up and efficiency is lost. That's not what we want, as she still needs a range to cross oceans ...

The efficiency losses at higher speeds are the result from the ship - as it creates its own bow wave - climbing up that wave, pushing - by rotational forces - the much wider stern under water. The results? Much higher drag, reduced efficiency, loss of range, or a lower cruising speed.

In order to counter the huge rise of drag resistance at high cruising speeds, we need to counter the rotational movement that pushes the stern deeper in the water. A trim wedge is added to the ship's stern design. The idea? As the ship speeds up and starts to rotate, the wedge helps push the aft ship out of the water, thus countering drag by reducing this rotational movement. I wanted a simple construction without moving parts, so a trim wedge, integrated in the aft underwater hull design, was the best solution.

The NA thought he'd figured out the right sizes and angles, but we both felt that CFD (computational fluid dynamics) could help out in selecting the best trim wedge design. To that effect, we designed five different trim wedges and used CFD to establish the effects on the rotational movement, overall resistance, etc. The goal was to find the optimal solution between a lower hull resistance at speed, taking into account that a trim wedge by nature uses resistance to counter the ship's rotational movement.

We made five cases / calculated through five designs. Here are some pics of the outcomes. A bow view of the hull slicing through the water at 10 knots, the associated wave field it creates, and the comparison of the five design cases. Nr. 4, as originally proposed by the NA, was the winner. Relative to no trim wedge, the optimized trim wedge design results in a 10% efficiency gain at 10 knots cruising speed.

Regards, Edwin & Veronika.

[North Baltic sea]

Hi,

here a similar already designed LRC

https://www.youtube.com/watch?v=q0y6NnhVb-c

Home page
https://www.artnautica.com/designs/l...nge-cruiser-58

LRC58: a fuel-efficient boat.
Loa: 17.6m

Beam: 4m

Lwl: 17.4m

Draft: 0.85m

Heavy Displacement: 14 tonnes

Engine: 75-90 hp

Fuel: 3,800 litres

Fuel efficiency: 0.80 litres per nautical mile

Water:1,300 litres

Cruising speed 7-8 knots

Range: 5000 nautical miles @7 knots

[Hippocampus]

That design evolved. Several were built as twins. Denis went forward with listening to owners and now builds a 65 and 78. They ocontinue to build in Europe and NZ. A truly remarkable boat. I’m sure Hammerhead will be as well. In this day and age think there’s reason to refine the legacy of Dashew’s thinking about long range cruising boats. Compared to the Korvets and Arksens think the Artnauticas are more KISS so possibly have an advantage for the mom and pop cruiser.

[twistedtree]

Originally Posted by Salty Pelican

As the LM65h is designed to cruise at relative high speeds, close to its hull speed, there's - with traditional water displacement designs - a design challenge we needed to overcome. As a water displacement design encroaches hull speed, resistance goes up and efficiency is lost. That's not what we want, as she still needs a range to cross oceans ...

The efficiency losses at higher speeds are the result from the ship - as it creates its own bow wave - climbing up that wave, pushing - by rotational forces - the much wider stern under water. The results? Much higher drag, reduced efficiency, loss of range, or a lower cruising speed.

In order to counter the huge rise of drag resistance at high cruising speeds, we need to counter the rotational movement that pushes the stern deeper in the water. A trim wedge is added to the ship's stern design. The idea? As the ship speeds up and starts to rotate, the wedge helps push the aft ship out of the water, thus countering drag by reducing this rotational movement. I wanted a simple construction without moving parts, so a trim wedge, integrated in the aft underwater hull design, was the best solution.

The NA thought he'd figured out the right sizes and angles, but we both felt that CFD (computational fluid dynamics) could help out in selecting the best trim wedge design. To that effect, we designed five different trim wedges and used CFD to establish the effects on the rotational movement, overall resistance, etc. The goal was to find the optimal solution between a lower hull resistance at speed, taking into account that a trim wedge by nature uses resistance to counter the ship's rotational movement.

We made five cases / calculated through five designs. Here are some pics of the outcomes. A bow view of the hull slicing through the water at 10 knots, the associated wave field it creates, and the comparison of the five design cases. Nr. 4, as originally proposed by the NA, was the winner. Relative to no trim wedge, the optimized trim wedge design results in a 10% efficiency gain at 10 knots cruising speed.

Regards, Edwin & Veronika.

Great stuff. CFD sure is an amazing tool for boat designing.

[Salty Pelican]

Thanks. it is an amazing tool indeed!

Takes the guessing out of boat design. Well, to a large extend, at least.

Regards, Edwin.

[Salty Pelican]

Happy new year to y'all!

Regards,

Edwin & Veronika.

[Salty Pelican]

So, the design team started working again last week. Mast will be telescopic and on the foredeck. That way we can have the ship low enough even for the French inland waterways. Flir will come on the roof/hood of the main room. A more stable platform than the mast, which seems important for Flir.

On a completely other note: we are thinking of transporting our current 41 feet Bruijs Kotter to Croatia and tour the islands coming summer. Anyone any experience with motor yachting in that area?

Regards, Edwin & Veronika.

[Salty Pelican]

Currently enjoying a week in Budapest, Hungary. We'll fly back again to the Netherlands tomorrow for a meeting with our NA. Second design cycle is finished. Starting the third and final one next week. Search for a good yard that can help us build our boat is on!

Regards, Edwin & Veronika.

[Mako]

Edwin since you’re planning on marketing this boat as a new model have you thought about attending some boat shows with a nice booth and beautiful renders? That way you can obtain real world feedback before you start cutting plates.

[Salty Pelican]

Hi Mako,

We intend to have the website up and running next month. Boat shows will definately be visited after we're done building her. I want the boat on display, for sure.

We won't use the boat shows to get feedback on the design, though, so no pre-build show visits.

Regards, Edwin.

[JWellington]

Looks like an Arksen 65. Why not just order one of them? They did all the work and can modify.

[Salty Pelican]

Maybe on first glances, but I think we made better choices on sea state comfort and efficiency.

Regards, Edwin.

[JWellington]

Originally Posted by Salty Pelican

Maybe on first glances, but I think we made better choices on sea state comfort and efficiency.

Regards, Edwin.

Fair enough, all the best. Im sure it will be a great boat.

[Salty Pelican]

Thanks JWellington,

The whole team is working passionately to bring our dream to life! Team meeting tomorrow that'll take the better part of the day for final design directions and considerations. More info on the LM65h project a few days later, that we can share here on the forum.

Thank you all for chiming in and giving your feedback!

Regards, Edwin & Veronika.