Size-based maintenance cost differences between boats.

[LandlockedInUT]

Howdy all, question time once again!

I've read all over the internet that a bigger boat is more expensive to maintain than a smaller one. Things like slip fees, haulout, bottom paint, ect are all mentioned as being more expensive on the bigger boat because it's bigger and that stuff is billed based on size and/or weight. So duh, obviously that part's more expensive. But what about all the other stuff that all boats have regardless of size? Note- I'm not comparing fuel burn, acquisition, or insurance costs, either.

Let's talk about a generic 43' and 53' twin screw boat. Both boats have two engines, a generator, three or four AC units, appliances in the galley, two or three heads, a water heater, a holding tank, a potable water tank, and all the associated plumbing.

In that regard, is there really much of a difference in maintenance cost? Thanks, and I look forward to reading the replies!

*edit- this is of course assuming that all work is done by the owner and not a yard.

 

[Slowmo]

A boat yard manager gave me a rule of thumb that maintenance costs double for every 5' of length. I don't know how accurate that is but thinks like the surface area of the hull goes up by the square of the length (for polishing, painting, etc). Also moorage costs not only go up by length the cost per foot often is higher above 45-50 feet. In theory if the same engines and auxiliaries were installed in a boat of two different LOA then the cost to maintain those would be the same. However, the reality is engine size and cost often goes up with size (more power needed), generators get larger, and AC needs are higher etc. If you did ALL he work yourself then other than moorage the costs may not differ by that much but I'm finding that environmental laws make it increasingly difficult to do your own work.

 

[Bacchus]

I would venture a guess that "on average" as you increase boat size by 10ft increments that you will likely find more or more complex equip / systems.
Yes 2 engines, a gen, etc.
Again I'd guess that 3 heads more common on 50 fters than 40 fters
Same w # of AC units
Batty bank size, inverters, increase to handle more equip & systems, more charging sources?
Some larger sizes have 2 gens... a small and a larger one
Multi fridges, Freezers, ice makers
Larger dingy, eng, cranes?
Thruster(s)
Hydraulic equip / systems
More complexity in electronics, networks, nav & entertainment systems
Summer kitchen on flybridge in addition to galley

 

[Delta Riverat]

My 44 foot Gypsy just fits in a 50 foot covered berth. Covered berths over 50 feet are hard to find.

 

[bowball]

Engines become bigger as some point and more expensive for routine maintenance.

 

[DDW]

Best rule of thumb is displacement. You pay for boats and boat parts by the pound. Displacement goes up with the cube of the length. Twice as long will cost 8x.

 

[Simi 60]

Well, as somone who actually has a largish boat I'll go against the opinion here and say the bigger boat can be cheaper with a couple of caveats

One of those is actually using the boat.

As full time cruisers we don't pay for a marina
Nor do we have to pay for a house to live in or a car
That money saved more than covers the cost of our vessel and mostly paid for maintenance

Also, pick the right boat and you don't need half the things you mention

We are 60 ft
* Single engine
* Single Genset but rarely used as plenty of roof space for solar
* No air con - we live cruise sub tropical to tropical but large overhangs , tinted windows and plenty of ventilation keeps her cool
* Water heater is a household 240 model, we are about to replace it with a smaller unit and they are $400.
* Appliances and multiple refrigeration are all household 240v so cheap to buy and replace and all run off of inverter/battery/solar
*2 heads - probably $30 in parts and a couple of hours to service in 6 years of usage
* Large tender yes but our 4.3m aluminium dory doesn't get damaged by sun or deflate and its size let's us anchor miles away and save fuel by using tender for reprovisioning
* Davits with cheap manual 3 speed trailer winches easily lift it + 30hp + battery + 25 litres of fuel from the water by myself, no hydraulic crane required.

Electronics, nav and entertainment need be as complex and expensive as you want them to be....or not
TV screens and monitors cost a couple of hundred $$
Lenovo tiny PC or similar to run nav also cost a couple of hundred $$
OpenCPN is free
It can also run all music, movies etc.and connect to the interwebs
None of our nav gear is integrated or networked with anything, all stand alone, all (apart from non essential radar) can be swapped out with a spare in under an hour

6 years out here full time, never needed a marina, wouldn't change a thing

 

[tiltrider1]

Its hard to answer the OP's question. You can go from a 42' to a 48' and find the costs don't change much. Both boats will use the same size engines and will come equipped similarly. Then you can have two 42' length boats and because of engines and equipment one can be considerably more expensive to maintain.

Every 10' seems to double the maintenance cost but that assumes the boat is getting wider as it gets longer. Some boats just get longer.

In general a boat that only requires DD 671's is considerably cheaper to maintain than one that requires DD8v71's. When you jump up an engine class suddenly you jump up in shaft size, prop size and so on.

So are you only adding 10 feet or are you adding double the volume and with that are you doubling the fancy equipment and are you upgrading the quality of the common equipment?

 

[O C Diver]

Probably the only fair way to address this would be to buy two new boats of the same model (different length) and use them identically.

The point that I'm making is that there are just too many variables between, boats, age, previous useage, current usage, how hard they're used, how well they have been maintained in the past, how and where they're kept, etc to make any reasonable comparison. Add to that the quality of the components. Without disparaging any manufacturers, some choose much better components with a much longer life expectancy, where others build to meet a price point.

Finally, there is the owner. Some seem to do near zero maintenance. Others seem to be pretty thorough on maintaining their boats. Then there are those who are constantly upgrading or upsizing their boat(s). Which category does the OP fall in?

Ted

 

[psneeld]

Complexity of systems is a major factor.

 

[LandlockedInUT]

Finally, there is the owner. Some seem to do near zero maintenance. Others seem to be pretty thorough on maintaining their boats. Then there are those who are constantly upgrading or upsizing their boat(s). Which category does the OP fall in?

Ted

Currently just a dreamer/planner as we're a few years off from making the step. I figure that I should be reading and asking questions in the mean time and as such, I read more than one forum and I like to fact check some of the suspected hyperbole I come across. Currently, the big picture is starting to reveal several paths to take and the answers to the questions will help us make informed decisions.

But to answer your question- if I had to pick, I'd be on the extreme side of thorough with an eye on correcting prior hack jobs, and improving reliability and ease of maintenance on existing systems. I treat almost everything I work on like I did the military aircraft I used to work on- every job has the direct and indirect potential to cause loss of life and property, so make damn sure it's done by the book down to the letter, no exceptions.

 

[O C Diver]

Currently just a dreamer/planner as we're a few years off from making the step. I figure that I should be reading and asking questions in the mean time and as such, I read more than one forum and I like to fact check some of the suspected hyperbole I come across. Currently, the big picture is starting to reveal several paths to take and the answers to the questions will help us make informed decisions.

But to answer your question- if I had to pick, I'd be on the extreme side of thorough with an eye on correcting prior hack jobs, and improving reliability and ease of maintenance on existing systems. I treat almost everything I work on like I did the military aircraft I used to work on- every job has the direct and indirect potential to cause loss of life and property, so make damn sure it's done by the book down to the letter, no exceptions.

Ok, so you can divide the costs into 3 categories:

Mechanical and functional maintenance has a modest and reasonable cost (if doing it yourself). This would include normal preventitive maintenance on all systems, painting the bottom, and replacing anodes. It certainly costs more as boats get larger, but it grows exponentially if you're paying others to do it.

Cosmetic maintenance is as it sounds cleaning, waxing and polishing to maintain the appearance and functionality or everything. Material costs are low; your labor is the big component. As above costs grow exponentially if you're paying others to do it on bigger boats.

Upgrading is where the real money is spent. In many cases the materials cost more than the labor if someone else is doing it. Here to the size of the vessel can hugely impact the upgrades. Upgrading a generator can be expensive on a 40' boat. On a 50' boat it can be heart stopping.

In summary, I wouldn't fear the larger boat if you're doing most of the labor. Upgrading is where you get into trouble.

Ted

 

[Simi 60]

This would include normal preventitive maintenance on all systems, painting the bottom, and replacing anodes. It certainly costs more as boats get larger, but it grows exponentially if you're paying others to do it

It does but by how much?
For example, pressure blast here in many places is part of lift price regardless of hours
Bottom takes a day to spot prime and paint

. Upgrading a generator can be expensive on a 40' boat. On a 50' boat it can be heart stopping.

How so?
If anything it should be an easier install, more space, so cheaper.

 

[LandlockedInUT]

What we'll be looking at will be old enough to have already had at least one cycle of upgrades done. I'd much rather pay more for a boat that's already been upgraded (stabilizers, for example), than pay to have them installed because you can't finance projects.

As for the upgrades themselves, I know the first year or so will be addressing existing issues and catching up on deferred maintenance but beyond that, it'll just depend on the boat and what our time on it will tell us to do. We've no intentions of any major interior refits or repowers and most of the upgrades will be to add redundancy and/or safety such as installing a high-capacity alternator rather than a backup gen set, addressing lightning protection and having minimalist disconnected backup electronics in the event we do get hit, and installing extra railing and hand holds.

And lastly to address a point touched on previously... we will be full time cruisers with every effort made to avoid marinas except for fuel and pump outs, hence the disregard of slip/dockage fees in the original question. We're getting on a boat to get away from people; if we wanted to park ten feet away from everyone, we'd get an RV and live in KOA campgrounds.

 

[O C Diver]

How so?
If anything it should be an easier install, more space, so cheaper.

The difference in price between a 10 and 20 KW generator.

Ted

 

[Simi 60]

The difference in price between a 10 and 20 KW generator.

Ted

Who says you need a 20kw generator?

We have a 7kw on a 60fter, gets used on rainy days, solar does it all on sunny days

Would have same size on a 40 fter but wouldn't be able to have as much solar

 

[O C Diver]

Who says you need a 20kw generator?

We have a 7kw on a 60fter, gets used on rainy days, solar does it all on sunny days

Would have same size on a 40 fter but wouldn't be able to have as much solar

Simi, normally I agree with you, but I really doubt 7KW is normal for a 60' boat. You could certainly live without a water heater, refrigerators, a comfortable bed, and a whole lot of other things on your boat, but you choose not to. For a lot of people boating in the tropics, air conditioning is as important to them as your comfortable bed is to you. If they have a 50'+ boat 7KW isn't going to get it done.

Ted

 

[LandlockedInUT]

The difference in price between a 10 and 20 KW generator.

Ted

I can't recall ever seeing a 53' boat with a 20Kw generator. Not that I'm speaking from experience, but that seems like such overkill. Of all the window shopping I've done online, most have one in the 10-15Kw range, and there's been a few with two- a 12.5 and a 7, for example. And yeah... cost... what's the average, something like $1000- $1500 per Kw of output?

I'd rather install a couple 250A alternators on one of the mains for about half the cost of a 5Kw genset, and use them as the under way and backup generator.

 

[O C Diver]

I can't recall ever seeing a 53' boat with a 20Kw generator. Not that I'm speaking from experience, but that seems like such overkill. Of all the window shopping I've done online, most have one in the 10-15Kw range, and there's been a few with two- a 12.5 and a 7, for example. And yeah... cost... what's the average, something like $1000- $1500 per Kw of output?

I'd rather install a couple 250A alternators on one of the mains for about half the cost of a 5Kw genset, and use them as the under way and backup generator.

Not uncommon for larger boats to run a hydraulic pump off the generator. Was recently on a Northern Pacific that had the stabilizers running off a hydraulic pump on the front end of a 20KW. Krogen had several models where the hydraulic pump for the bow thruster and other hydraulic devices ran off a generator mounted pump.

You did say you wanted stabilizers in a previous post didn't you?

Ted

 

[LandlockedInUT]

Not uncommon for larger boats to run a hydraulic pump off the generator. Was recently on a Northern Pacific that had the stabilizers running off a hydraulic pump on the front end of a 20KW. Krogen had several models where the hydraulic pump for the bow thruster and other hydraulic devices ran off a generator mounted pump.

You did say you wanted stabilizers in a previous post didn't you?

Ted

That's a very good point; thank you. That's what I get for making blanket statements. What all we've been looking at have electric thrusters and some don't have one at all. I assumed that the stabs were run off a pump on one of the main engines as none of what we've been looking at have zero speed fins.

 

[O C Diver]

That's a very good point; thank you. That's what I get for making blanket statements. What all we've been looking at have electric thrusters and some don't have one at all. I assumed that the stabs were run off a pump on one of the main engines as none of what we've been looking at have zero speed fins.

A lot of stabilizers run off of one main engine. One of the advantages to a hydraulic pump running off a generator is the pump running off a constant speed motor. No need to increase RPM on the main engine to improve bow thruster performance while docking. I'm not sure if that's an advantage in fin performance at slow speeds.

Ted

 

[LandlockedInUT]

I've never read anything about stabilizers not performing at low speeds due to lack of pump RPM, but I do see it mentioned that slower speeds may require larger fins to remain effective. The boats in question are from Hatteras; I've never seen one in the size range discussed with a hydraulic thruster, but plenty have stabs. Most people on this board it seems, are in the PNW and as it's also a trawler forum, I'd expect most input to be from that frame of reference.

Regardless, I completely agree with you about running hydro off a constant speed engine and if that were something we'd ever want to upgrade to, a bigger genset would most likely be mandatory.

Thanks!

 

[Simi 60]

Simi, normally I agree with you, but I really doubt 7KW is normal for a 60' boat. You could certainly live without a water heater, refrigerators, a comfortable bed, and a whole lot of other things on your boat, but you choose not to. For a lot of people boating in the tropics, air conditioning is as important to them as your comfortable bed is to you. If they have a 50'+ boat 7KW isn't going to get it done.

Ted

We do boat in the sub tropicals to tropics
Brisbane is the same latitude as Florida at 27 degrees

People in large sailing catamarans are running A/C on as small as 2kw Genset and LFP batteries
Some even claim to run on batteries alone

Using an A/C size calculator a 15ft X 15ft room needs a 2.7kw air conditioner

Given that, 7kw "should" be plenty

But, for boats that have below deck cabins adjacent to hot ER
Little to no shading
Angled windows that see a lot of sun then yes, they could we'll need more to cope.

 

[tiltrider1]

I can't recall ever seeing a 53' boat with a 20Kw generator. Not that I'm speaking from experience, but that seems like such overkill. Of all the window shopping I've done online, most have one in the 10-15Kw range, and there's been a few with two- a 12.5 and a 7, for example. And yeah... cost... what's the average, something like $1000- $1500 per Kw of output?

I'd rather install a couple 250A alternators on one of the mains for about half the cost of a 5Kw genset, and use them as the under way and backup generator.

250A alternators sounds like a serious headache to add to a boat. I’m not going to say you can’t do it but I don’t believe you will end up finding it an advantage over a genset. It is very common for me to run the genset while motoring in the winter. It allows me to run my heat pumps and often the wife likes to do laundry while we are motoring.

 

[Simi 60]

I'd rather install a couple 250A alternators on one of the mains for about half the cost of a 5Kw genset, and use them as the under way and backup generator.

I've mentioned it on here before but it's been poo pooed somewhat as it requires constant rpm, which is easy for us, we run 1150rpm everywhere

Mech Alte 10kva alternator/Genset heads are $500 and about the size of a big alternator

Some talk on this thread
https://www.trawlerforum.com/forums/s4/load-dump-lifepo4-generator-battery-charger-62840.html

 

[LandlockedInUT]

250A alternators sounds like a serious headache to add to a boat.

How so? I've fabbed up brackets and spec'd additional pulleys to add secondary alternators, a hydraulic pump for a winch, and air compressors to existing engines on a few Land Cruisers I've had, so I don't think that part of the install would be any different. Or did you mean everything that goes between the alternator and the battery bank? On that side of the install, would it be any different than installing a generator?

To me, alternators make more sense if you're adding to your existing electrical production than a second generator.

Two of these will make 4.7Kw.
https://marinesmartenergy.com/produ...12-volt-250a-alternator-and-remote-rectified/

Compared to a 4.5Kw generator...
https://citimarinestore.com/en/phas...ltage-120_240v/2700-phasor_sound_enclosure-no

Right off the bat, the alternators cost half of what the generator would, and with the alternators, you don't have to install fuel lines, a through hull, plumb an exhaust, and you won't have the cost of a haulout, a boom truck/forklift/crane and other yard fees, nor would you have to cut an access hole to get it in the boat if the location it's going in to requires one. Alternators will eliminate the maintenance that a generator will require (oil, filters, impellers, heat exchanger, ect), weigh about 1/3 what the generator would (about 50 lbs. per alternator vs. 300 for that Phasor), and take up a fraction of the space a generator would. I think these things are primarily marketed towards sailors as those last two points seem to be critical for them. For the cost of that Phasor, you could have four alternators making 9Kw, more or less eliminating the need for a generator altogether.

I'm not trying to sell anyone anything so if I'm missing something, I'd very much like to hear it.

 

[LandlockedInUT]

I've mentioned it on here before but it's been poo pooed somewhat as it requires constant rpm, which is easy for us, we run 1150rpm everywhere

Mech Alte 10kva alternator/Genset heads are $500 and about the size of a big alternator

Some talk on this thread
https://www.trawlerforum.com/forums/s4/load-dump-lifepo4-generator-battery-charger-62840.html

If you're running a gen head from one of the mains, I can see the point about constant RPM. I've seen a few pictures of some goofy homebuilt setups with a CVT from a snow mobile to keep the gen head at a constant RPM as the main engine speeds up and slows down. The alternators I linked to in my previous post are regulated and rectified same as the alternators in all our cars and since they're producing DC voltage, there's no need to maintain a certain RPM. Besides... the RPM range on those GenMaax alternators would allow them to be pulleyed to make max power at engine idle without worry of overspeeding them at WOT on a diesel engine, and the regulator and rectifier make sure they're delivering rated power and voltage at all times.

I'll go have a read on that thread now; thanks!

 

[JD Ray]

To me, alternators make more sense if you're adding to your existing electrical production than a second generator.
…
Right off the bat, the alternators cost half of what the generator would, and with the alternators, you don't have to install fuel lines, a through hull, plumb an exhaust, and you won't have the cost of a haulout, a boom truck/forklift/crane and other yard fees, nor would you have to cut an access hole to get it in the boat if the location it's going in to requires one. Alternators will eliminate the maintenance that a generator will require (oil, filters, impellers, heat exchanger, ect), weigh about 1/3 what the generator would (about 50 lbs. per alternator vs. 300 for that Phasor), and take up a fraction of the space a generator would. I think these things are primarily marketed towards sailors as those last two points seem to be critical for them. For the cost of that Phasor, you could have four alternators making 9Kw, more or less eliminating the need for a generator altogether.

Have you looked at parallel hybrid electric drivetrains at all? They mount an electric motor on a pulley system that connects to a gearbox. You can run the engine and not the motor at all; run the engine and use the motor as an alternator to charge your batteries; or use the motor without the engine in pure electric drive mode for quiet cruising at low speeds. Also, with a genset available, the system acts as a “get home” drive.

Or so I understand. I’m new to this all as well.

 

[LandlockedInUT]

Have you looked at parallel hybrid electric drivetrains at all? They mount an electric motor on a pulley system that connects to a gearbox. You can run the engine and not the motor at all; run the engine and use the motor as an alternator to charge your batteries; or use the motor without the engine in pure electric drive mode for quiet cruising at low speeds. Also, with a genset available, the system acts as a “get home” drive.

Or so I understand. I’m new to this all as well.

I've heard of them, yes. At this risk of throwing this way off track, I'll go out on a limb and simply say that it's more efficient to use the diesel engine to directly turn the prop on anything that you expect useful range from. A lake boat would be an exception and it looks like that's where hybrid electric and fully electric propulsion will make its first mainstream entrance into the marine sector.

As for the get home factor, I'm firmly entrenched in the twin screw camp, but that's an entirely different discussion. We're already off in the weeds from the original question, but it's all good info so I'm just rolling with it.

 

[Simi 60]

If you're running a gen head from one of the mains, I can see the point about constant RPM. I've seen a few pictures of some goofy homebuilt setups with a CVT from a snow mobile to keep the gen head at a constant RPM as the main engine speeds up and slows down!

Why would the engine speed up or slow down?

Puts it in gear, push lever forward to required RPM and there it stays.