Considering a Spirited 480 new build

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Velas
Posts: 8
Joined: Wed Mar 16, 2016 10:09 am

Considering a Spirited 480 new build

Post by Velas » Sat Mar 19, 2016 1:53 am

I've been looking at the Spirited 480. It looks lovely. I have almost pulled the trigger. A few things are stopping me.

The major being the engine bay and the saildrives. They look a lot like the original 380 which had water ingress and the mods prevented the engines from coming out.

Judging from the Mick's photos, the hatch is on the third step from the back, instead of the second. Still too low IMHO.

What is your optinion ?

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Considering a Spirited 480 new build

Post by 44c » Sat Mar 19, 2016 7:27 pm

Well, you asked for an opinion.... IMO if your only problem with the boat is the engine hatches, then you should discuss altering them with the designer.

Any good designer will be able to accept that the boat may not be perfect, that his boat could be improved in some ways, or that it might not 100% suit everyone in standard form.

This isn't a major structural modification you're talking about, it's just a minor tweak.

Velas
Posts: 8
Joined: Wed Mar 16, 2016 10:09 am

Re: Considering a Spirited 480 new build

Post by Velas » Sun Mar 20, 2016 8:24 pm

Hey 44c, you're everywhere ;)

I know the back hatches are a sore point, that's why I ask. Perhaps I should send Mick a PM.

The original hatches on the 380 are supposedly a problem (perhaps due to bad builds and not a design problem). The modified ones are even worse (imho). Granted, they don't leak. But I doubt they can survive a real wave slamming on top and are slippery in day-to-day usage.

I have been toying with the idea of ditching the SD all together and go with electric and driveshafts under the rear bunks. Might actually make a lot of sense. "Free" power while under sail. A single bank of batteries. No noise during motoring (for a lack of better term). No smell (unless it burns). Less annoying when sleeping etc etc..

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Considering a Spirited 480 new build

Post by 44c » Mon Mar 21, 2016 4:13 pm

Hmmm.... so where does the electricity come from?

Consider how powerful an electric motor will need to be to drive a 50 foot cat at a reasonable speed, and how long that motor could run off batteries alone. The consider how you're going to recharge those batteries.

You can certainly do electric motors, but in unless you're just going to motor out of a marina, sail around for a bit, then motor back in to recharge, you'll really you need a diesel genset to make them practical.

But if the problem with the engine hatches is just one of poor build quality, then it's simple really - make sure you do a better job than the ones who had problems.

A couple of friends slightly altered the rear step set up on their S380's, in a way which made the hatches easier to build and seal. They're made of the same material as the standard setup, and covered with the same non-skid. So I can't see how they could be any weaker or more slippery than the standard ones.

Velas
Posts: 8
Joined: Wed Mar 16, 2016 10:09 am

Re: Considering a Spirited 480 new build

Post by Velas » Tue Mar 22, 2016 9:01 am

I'm sure the hatches can be made properly. But I've seem some made "professionally", which are just plain window hatches placed on the second step (instead of second+third as in the original design). They're slippery (unless covered with adhesive antiskid) and look plain ugly. Not to mention the fact that you need to rip the boat to get the engine out.

The electric motors can be done in a smart way. I'm getting inspiration from here: http://www.catbuildingblog.com/the-elec ... rrow-1200/

44c
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Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Considering a Spirited 480 new build

Post by 44c » Tue Mar 22, 2016 10:57 am

He's fitting a pair of 3.6kW electric motors, and expects the boat will have similar performance to having a pair of 15kW diesels. I'm pretty sure he's going to be disappointed.

Even worse, he (from what I can make out) is powering this with a 2.4kW genset. So he won't even have the full 7.2 Kw available for any length of time. 2.4 Kw will maybe push a boat like that at about 3-4 knots in dead calm conditions. Any headwind and he's going to be going seriously slow...

He's also incorrect in his statement that electric motors have a constant torque delivery over the RPM range. They don't. Electric motors have a constant POWER delivery. Since power is essentially torque x RPM, this means electric motors deliver maximum torque at zero RPM, and as revs increase, available torque decreases.

This is excellent for direct drive on wheel driven vehicles. When you want maximum torque, getting away from a standstill, it's there.

However it doesn't apply for propeller driven boats. As RPM increases, the demand for torque increases. (It takes more torque to turn a given prop at 1500 RPM than it does at 1000 RPM) Also the need for maximum torque at zero RPM simply doesn't exist. Boat motors don't stall when you put them in gear. Because propellers slip.

44c
Posts: 1148
Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Considering a Spirited 480 new build

Post by 44c » Tue Mar 22, 2016 11:32 am

Just want to say - you can certainly do a diesel/electric system and make it work. But you need to be realistic about the power requirements. There's nothing magical about electric motors, that says you can replace a 15kW diesel or outboard with a 5 kW electric, and get the same result. It just won't happen.

But if you specify the right size motors, and a genset big enough to run them for prolonged periods it will certainly work. What will be questionable then though, is whether any fuel savings would ever pay for the extra initial cost.

Velas
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Joined: Wed Mar 16, 2016 10:09 am

Re: Considering a Spirited 480 new build

Post by Velas » Thu Mar 24, 2016 6:29 am

44c, you have good points.

The guy (a professional sailor, btw) says: "Is the chosen power enough? For now I have to rely on the calculations Greenstar did for our boat.". This is like asking the host if the wine is good :lol:
He'll be launching in two-three months, so I'm waiting to see what happens.

I share most of your doubts regarding the power.

The idea of mixed diesel+electric appeals to me, however. You can not always have the 100% on both motors, but a single diesel + single electric in the other hull makes economical sense. With enough solar (and maybe hydro) some energy could be harvested to reduce the amount of diesel required on passages.

44c
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Joined: Tue Aug 08, 2006 5:08 am
Location: Hervey Bay, Qld

Re: Considering a Spirited 480 new build

Post by 44c » Thu Mar 24, 2016 8:21 am

Yeah, I expect there will be glowing reports of it's performance initially, when the boat is really light, has no rig on it etc... but once it's loaded for cruising, I can't see those motors doing the job. I certainly wouldn't want to be crossing a bar in a 40 foot boat with 7kW total motor power. (And maybe only 2.4 available :shock: )

To be honest, if you build a boat that sails well, especially in light winds - and the S480 will certainly fit that description, you're not going to be using huge amounts of diesel anyway. We run outboards, and use maybe 60 - 80 litres of fuel per month - and probably half of that goes into the dinghy. (Which has an 18hp 2 stroke, so is quite thirsty). Full-time liveaboard cruising.

You might save fuel going with a hybrid, but on a sailing boat that actually sails, it could take an awfully long time to recover the extra costs involved.

Renewables, wind, solar etc, are great for house loads. But really not much use for propulsion loads. 2kW hours is a lot of power when running fridge/watermaker/lighting etc. But a drop in the ocean for propulsion. MAYBE enough to move you a mile or two?

I think a lot of people see how comparatively fuel efficient hybrid cars are, and think it will carry over to boats. But the way the engines are used is quite different. Conventional cars waste a huge amount of fuel in traffic, sitting ldling, going nowhere. On the open road, hybrids really aren't much (if any) more efficient than a similar conventional car. Boats operate on the "open road" most of the time. When motoring, (mostly because the BOM got the forecast wrong, yet again...), 99% of the time you set the throttle to an efficient cruising speed, and leave it there.

mikeb
Posts: 136
Joined: Wed May 26, 2010 3:01 am

Re: Considering a Spirited 480 new build

Post by mikeb » Thu Mar 24, 2016 1:45 pm

I love the 'idea' of going electric but as much as I wanted too I couldn't make the numbers work. The additional cost, in setting up the whole system with generator & relatively large battery bank, was too great for me. 44C makes a great point around fuel consumption, ie the recovery of the additional upfront costs will take a very very long time with the relatively small number of litres actually used. I hope in time the costs will come down, especially in the batteries & motors, as I really think this set up is the way of the future...
Good luck with your decisions.

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