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Lessons from a Previous Yacht Build.

Updated: Mar 23, 2023

XPM78-01 Mobius was built by Wayne and Christine to a design by Artnautica. Both are very experienced sailors and good friends. Their design reflects their wishes, one tangible advantage of building your boat. The design for Vanguard has evolved from this, reflecting our wishes. So just what has been changed and why?

First off we need three yacht cabins. Master, family, and guest for want of a better description. Master cabin to be near the center of buoyancy as the most comfortable pace for one’s head. Family cabin to be easily accessed and the guest cabin to have its own access. If we carry crew, then they get their privacy. Cabins have both skylights and small through-hull ports; my wife is claustrophobic and likes daylight. On a 78-foot hull, this is easy enough to configure, though it necessitated lifting the saloon 300mm to gain headroom and reconfiguring the fuel tanks below.

We also extended the saloon forwards by 1000mm to give more room around the helm and the additional companionway. Looking at FPB and Arksen designs, they have some very well-laid-out arrangements in the main saloon, so we configured ours along similar lines and saved the brain pain. We also added double helm chairs so my wife can give me orders (Ha!). We thought the superstructure looked top-heavy with the raised saloon so to mitigate this, we added a 300mm bulwark from the foredeck to the midships. This extended the visual sheer line upwards a little. Freeing ports are included to shed water, and it should help keep the foredeck dry(er).

Mobius used a “flopper stopper” rig for stability and derricks for boat handling. She is set up for powered stabilizers but did not first-fit. We decided to go for stabilizers from the outset and save the additional top hamper. We selected DMS, and their Magnus effect rotors as their zero-speed performance is at least theoretically better than traditional or zero-speed fins. They will fold away to limit damage when moored alongside or maneuvering near ice.

Building Explorer Yacht XPM78-02 Vanguard

Now the interesting bit. Everything mission-critical had better be in duplicate or have a massive MTBF (mean time between failures). That’s standard commercial marine practice. So we went for two identical main engines, derated for continuous running but still produced twice the required installed HP. We have two gearboxes, two drivelines, two rudders. We also looked at adding a Hybrid drive. With surplus propulsive power, we can charge batteries much faster than is typical. We can drive two shafts from one engine or undertake all our manoeuvering in total silence on electric drive only. Dynamic positioning becomes straightforward to implement on an electric drive, independent rudders, and a bow thruster. The hybrid drive is not for everyone and requires some deep thinking on the intended goal, but that’s for a later discussion.

Finally, Wayne made a big decision that also suits our needs. That is to base all the electrical systems around the battery bank. Generators (shore, mechanical, PV) feed the batteries, and every other utility draws from them. We specified big battery banks (2x60kWh), but that’s no matter in these days of Electric Vehicles, and we need the ballast. We also picked marine Type Approved systems with their dedicated charging, heating, cooling, and safety systems included. With this bank and fast charging from the Hybrid, we do not need additional generators (that’s two systems gone!).

I could go on, and indeed, there are many small changes, but these are the majority of the more significant ones. What remains is to recalculate our stability curves with the new specification though I think we are good to go. Each to their own, as they say.

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