Category Archives: Think

Thoughts on alternative solutions, such as sail handling at the mast vs all lines led to cockpit.

Will it ever become a boat again?

Every winter it’s the same story; lot’s of maintenance and upgrade projects going on. The boat turns into something resembling a disorganized recycling center. But then things start to fall into place and after a final rush of getting the masts back on, it’s time to put the tools away and sail.


Mainly because of weather conditions, some contractor outsourcing (usually machining and welding), delivery times of goods ordered and time to do research, we need to have several projects going simultaneously.

Wind vane

After our post,, about the wind vane we put together for Anna, we have received a few requests for a little more info. So here’s a little video of the thing.


Basically, our misgivings about mounting the vane under the mizzen boom – supposedly made worse by relocating our two solar panels to the stern – were proven to be unfounded. However, we have so far not managed to get the vane to work with less than 2 knots boat speed, but maybe that is not to be expected. Light and fluky winds are not even easy for a human helmsman.

Apart from the obvious benefit of freeing the helmsman from the tiller, or wheel in our case, the main benefit of the wind vane is the substantial saving in power consumption when comparing with an autopilot. With the wind vane, we are self-sufficient as far as electricity goes with our two 54W solar panels – as long as it’s sunny…

Carbon monoxide

We ordered a carbon monoxide detector through ebay from China, installed it (well, put it on the cushion…) and fired up the POD kerosene heater and kept it running at full blast for an hour. The detector showed nothing. Then we hung it at the anti down draught contraption on the chimney. After some 10-15 minutes it showed 118 ppm.

So, obviously, some exhaust fumes are getting into the cabin although not sufficient to pose a serious problem, it seems. A different exhaust solution (another chimney cowl or a fan to force exhaust gases out) might keep us sleeping more soundly. More testing needs to be done.


Kerosene smell

After googling and some trial & error we have settled for the following treatment of the kerosene (Jet A1 fuel) which we use for our POD/GeHÃ¥ kerosene heater as well as lamps.

  • Add approx 1 kilogram of powdered limestone to 10 liters of kerosene. Shake and let settle for about 4-5 days. Siphon kerosene out of container so you don’t get the limestone sediment.
  • Mix 1 deciliter of isopropyl alcohol with a few drops of some essential oil (eg lemongrass oil).
  • Add the alcohol/oil mix to 10 liters of kerosene (1:100)

If the smell of the kerosene gets annoying (from spilling a little or messing with the burner…), leave a bowl with a little white vinegar overnight close to the source of the smell.
It is a little bit of work to treat the kerosene as above, but at a 70% cost saving compared to ‘lamp oil’, we feel it’s worth it.


A great web site on kerosene items is:

Heater alternatives

Prior to installing the kerosene heater (which heats the aft cabin and aft head only), we looked into


#1. Replacing our current Webasto HL3003 with a new forced air diesel heater
Benefits: Reduced draw on battery (approx 20-25% less at max setting). Reduced fuel consumption (approx 25% less at max setting). More control over settings (our current heater is either off or on full power). Can be fitted into our existing system of ducts. No new chimney needed. Uses same fuel as engine. Can be used while sailing/heeling.
Disadvantages: Cost (especially Webasto and Eberspächer, wheras Planar is less expensive). Does not supply hot tap water. Still draws about 10-60 W, depending on heat setting. Some noise.

#2. Changing to water heater
Benefits: Reduced draw on battery (approx. -50%), Reduced fuel consumption (approx -30%). Can be hooked into our hot tap water supply. No new chimney needed. Uses same fuel as engine. Can be used while sailing/heeling.
Disadvantages: Cost. Requires new distribution system + convectors. Still draws about 10-40 W.

#3. Kerosene heater (brand: POD)
Benefits: No, or minimal (1.2 W), draw on battery. Uses same fuel as lamps (we use our kerosene lamps every evening because we like them; it’s the brass, open fire thing). Almost silent. Cheap fuel (about 20% cheaper than diesel). Can be used while sailing/heeling.
Disadvantages: Smell (though not a lot, assuming that you set the wick at the proper level). Requires new chimney and new distribution system. Does not supply hot tap water.

#4. Propane/Butane heater (brand: Truma)
Benefits: Uses same fuel as cooker/oven. Can be used while sailing/heeling.
Disadvantages: Very expensive fuel (about 3 times the price of kerosene/diesel) – which is why we did not look into this further. Requires new gas installation.

#5. Diesel heater (brand: Glembring and Refleks)
Benefits: No, or minimal (1.2 W), draw on battery. Uses same fuel as engine. Almost silent.
Disadvantages: Requires new chimney and new distribution system. Does not supply hot tap water. Can not be used while sailing due to heeling.

In the end, how you weigh the different pros and cons depends on how you use the boat. For us, the wish to be able to anchor for a week in winter with no engine running required to produce electricity is an important aspect (we have a 12 V 400 A battery bank). In the end, that, combined with the cost of the Webasto and Eberspächer products, is what made us settle for the POD heater. Only later did we find the Planar brand heaters, which are about 50-70% cheaper than similar Webasto/Eberspächer, although the Planar heaters draw about 13-25% more amps, depending on the setting.

For us, even with the advantageous price of the Planar, replacing our forced air diesel heater would not have achieved the goal (no, or minimal, battery draw). But we are definitely considering the Planar for the future since it barely costs more than servicing a Webasto/Eberspächer.

When at anchor, and even more so when sailing, it is sufficient to heat the aft cabin and head (volume approx equivalent to a 25ft boat). The salon is difficult to heat when sailing, since crew passing up and down the companionway result in most heat being lost. Also, we rarely have people staying in the forepeak, nor use the forward head. Consequently, our basic heating requirement is about 1 kW. However, the possibility of occasionally heating the salon while at anchor, and even the forepeak, has some value and requires an additional 1 kW, which is the minimum setting on the new forced air heaters.

I couldn’t agree more…

In his book 500 SegelbÃ¥tar i test (500 sailing yachts tested) from 2005, Curt Gelin, a Swedish sailing journalist, writes about the Hallberg-Rassy 41; “In the middle of the 1970s, the Hallberg-Rassy 41 was my great ideal in terms of boats for extended cruising. This flagship, designed by Olle Enderlein, from the wharf in Ellös epitomizes total seaworthiness, strength and style. The fact is, still today, the HR41 is one of Olle’s most beautiful boats”.



New Doc 2_1


The open sea

The feeling of being out on the open sea in a boat is something which has an indescribable appeal to me. Yesterday I came across an interview with the Libyan/Touareg author Ibrahim Al Koni which caught my eye since, to me, the desert and the open sea are very much similar;

“The issue of the desert is an issue of being. The desert in is reality not a desert, but a symbol of human existence.
The desert is in reality ‘placeless’  and is therefore also the symbol of ultimate freedom; freedom because the encounter with the desert resembles the encounter with death.


Engine sizing

The guys who own Maringret, another HR41, have put up a calculation on their blog at of how they sized their new engine. It’s a great step-by-step calculation which shows an application of the chapter “Engine selection and installation” in Nigel Calder’s book Marine diesel engines (and if that doesn’t interest you, you should check out their collection of links) . Here’s how our calculations (leading us to aim for a 40hp engine) compare with those of Maringret (leading them to target 60+ hp).

Boat                                                             Maringret        Anna #1        Anna #2        Anna #3
LWL, m (ft)                                                   10.4 (34.1)      10.4 (34.1)    10.4 (34.1)    10.4 (34.1)
Bow wave velocity, knots                                  5.84                 5.84               5.84               5.84
SLR (theoretical)                                                  1.34                 1.34               1.34              1.34
Hull speed (theor.)                                              7.83                 7.83               7.83              7.83
Target max speed, knots                                     ??                    6.5                 7                   7.83
Displacement, tons (long tons)                     18 (18.29)        14 (14.2)      14 (14.2)        14 (14.2)
Water resistance, lbs / long ton                         55                     20                 28                   55
Total resistance, lbs                                          1006                  284              398                  781
Effective hp                                                         23.6                   5.5                8.4                18.3
Propeller efficiency, %                                        50                     65                 65                  65
Required hp                                                        47.2                  8.5                 13                28.1
Adverse allowance, %                                         33                     33                 33                  33
Target hp                                                              63                     11                  17                 37

The calculations are a great illustration of how the energy required increases exponentially as you try to push the boat faster than the bow wave. And that most boat issues are a matter of compromise and a consequence of intended purpose.

On the Volvo Penta web page, there’s a nice little engine configurator to identify the recommended engine size depending on length of waterline, displacement and required top speed;