Propulsion | Sailing Blog - Technical Hints and Tips - Sailing Television

Season 2 - Equipment Roundup

Well it’s been a great sailing season! We have never been so far north! We sailed almost 4 thousand miles and had a chance to fine-tune the new boat! Here is a round-up of new gear that stood out from this season of sailing!

Feathering Prop - Autoprop - Last year I lamented the lack of a feathering or folding prop since I felt we lost too much speed with the big fixed 3-blade prop. So this year we changed to an Autoprop. What a difference! Getting rid of a fixed prop has to be the first thing to do to improve performance. It’s like towing around a bucket. Dollar for dollar it must be the best way to get more speed. The Autoprop automatically adjusts its pitch depending on speed through the water and seems to work quite well.

Downwind Pole - Selden Carbon Pole - We have always had a downwind pole and use it to pole out one of the headsails when sailing right downwind. We hadn’t got around to installing it when the boat was new so we added it this spring. It’s a carbon pole and even though it is quite large it is easy to lift with one hand! We used it 6-7 times this summer. Mostly it was in quite light air when we might otherwise have had to motor. Nice to have it back!

Anchor tackle - Rocna 33KG + 80 meters chain - Norway this summer meant some very deep anchorages. We anchored in 12-18 meters of water a few times. Yikes! It was great having long chain and knowing we would be fine. And as usual the Rocna set beautifully. It is a great all around anchor.

Autopilot Remote - Raymarine Smart Remote - This is a little wireless remote to control the autopilot. It also includes a repeater for all the basic data (speed, depth, wind, heading, VMG etc). On cold or rainy days it is nice to stand up under the dodger (sprayhood) and steer with the remote. Sheryl can take it up to the bow when we are anchoring and check the depth before she drops the hook.

Electronic Charts - Navionics Charts + Apps - Electronic charting has come a long way in a few years. The newest charts are amazingly accurate, and now include lots of other data. Aerial photos of harbours we are approaching are a very nice addition. All tide data is also included so when we sailed in the Brittany coast and the tide exceeded 8 meters we could quickly find a tide station to check where we stood. Much quicker and easier than using printed tide table. Plus I have to recommend the Navionics App!! We have this on our iPhone and it’s amazing. All chart data, plus tides for the British Isles is included in an app for around $20!! How could you NOT buy this. It works for iPhone and there is a HiRes version for iPad. It also comes for Android devices. It’s great for planning (and even serves as a back-up for our chartplotter.)

Changing the prop on the beach

We put the boat up on the beach yesterday to change the prop.
Its been gorgeous weather since we arrived here last week. Its now neap tides so the total tide is just 2.2 meters. Our boat draws 0.9 meters with the keel up. This means we have to get on the beach near high tide so we will have a few hours after the water has fallen by the 1 meter we need to dry out.

We dropped our Fortress anchor as we came in so we would be able to pull back off after, and nosed up on the sand.
You can see the sand is quite hard - our skeg has just sunk in to the sand by about 4 inches.
New prop in place! Its an Autoprop and we’ll see how she performs over the season’s cruise.
The Autoprop is made by Bruntons in the UK. It is unique amongst propellors in that its blades find their own proper pitch depending on the situation. I am still a little fizzy on the actual science of this, but I understand the blade is offset from the hub (as you see above) and this allows it to rotate to accommodate the speed of water flowing past. If you are going slower (punching into a head sea or strong wind) then the pitch will be finer. If you are moving faster such as motor sailing - then the blades will take a much coarser pitch to match that.

On board preparations!

We’re back on board in Itchenor (South of England) getting ready for this year’s cruise. Weather is lovely - like summer actually as its 24 degrees and sunny, flowers blooming etc. Its even a holiday weekend!

Not much maintenance to do - just checking over systems ...

but I do have some NEW PROJECTS that didn’t get sorted last year

Carbon Downwind Pole - Lovely! - beautifully tapered at each end. Carbon might seem like a big expense on a downwind pole but the value is not so much performance as just being able to handle it. This pole is quite a bit lighter than our aluminum pole from our 37 footer Two-Step. So its much longer and stronger but lighter to lift and handle when setting it. I like to store the pole vertically on the mast so we have added a mast track and car to store it. To store on the mast the pole has a socket arrangement to connect it to the mast car. This allows for articulation without jamming when you set the pole (as opposed to a hook/piston going over a ring on the mast)

New Propellor - we sailed last year with a standard 3 bladed fixed propellor and really felt the drag. It is like towing a 20 inch diameter bucket around. We have a shiny new Autoprop this year and are anxious to test it out. Here David of Bruntons (who make the Autoprop) shows me how the bladed rotate to automatically find the correct pitch.

Equipment Roundup - Part 2

Rocna 33Kg Anchor - Excellent - In my opinion this is the best all-round anchor, working well in sand, mud and soft mud. It sets quickly and holds very well. It also sets well in most grass and weed although the Delta might outperform it there since it doesn’t have the ring on top. Basically most modern anchors will work well if they are big enough. This is one thing I really admire about Rocna - they recommend a realistic size anchor for a cruising boat. For our 49 footer we could have used either a 33kg or 40kg version of the Rocna according to their website. Other anchor manufacturers recommend much lighter versions but in the very small print they are talking about using it up to just 30 knots wind. I think similar anchor shapes like the Manson and the Spade might also perform well in similar sizes. But would need to be much bigger than they recommend. For instance, Spade Anchors recommend the 77ld (similar to our 73lb Rocna) would be sufficient for a 75 foot boat?! Rocna suggest their 73lb for 40-50 footers (66 feet only if the boat was an ultralight racer weighing less than 10t). Rocna tables - For real life cruising when you occasionally wake up at 3am in gusts of 40 knots you want to know you have been conservative in sizing your anchor! Here I inspect our Rocna at low tide after winds of 30-35 blew all night. Not budging!

Yanmar 4JH4 Engine - 56hp - Excellent!! - Very nice performing engine - well engineered. Affordable parts (versus certain other makes... not to name names). The instrument panel is abit cheesy but all my experience with the engine is positive.

3 bladed fixed prop - oops... not good - it certainly pushes the boat along nicely under power but a real drag under sail. We hadn’t ordered a feathering/folding prop for the 49 for this past summer cruise and really missed it!! The Variprop we had on the 42 was excellent. Will probably go for another on the 49 for this season. Definitely we need to change from the fixed prop. It is certainly the best way to improve performance on any sailboat. We’ll go at least 1/2 knot faster under sail and I think closer to 1 knot in some situations.



As we are sailing right now in the Tyrrhenian Sea off Italy, we have had many days I thought it would be great to have a feathering prop. For the past two weeks there have been quite light winds and flat seas. Yesterday on the way to Tropea (a gorgeous gem if you get a chance to visit!!) there was just 5-9 knots of wind most of the way. We sailed as best we could and just enjoyed the flat seas and spectacular coastline. But I kept thinking we would be able to make more of the light winds if we had a prop with less resistance. If we are sailing at 4 knots and our 3-bladed prop is spinning – we will slow down to almost 3.5 if I put it in gear. General consensus is that a feathering or folding prop would give you in the area of one extra knot under sail. And its often those very calm days when that would make the difference between sailing and having to switch the engine on. The difference between sailing with a feathered prop and towing a fixed-blade one through the water has been described as similar to dragging a bucket around. And who wants to do that?!?

So the new boat is definitely going to have a feathering prop.

One problem with a new propellor, especially on a new boat, is knowing what the pitch and diameter should be. With Two-Step we got it fairly close so we didn't need to change anything. Nevertheless, after a few years I decided we might reduce the diameter and try to reduce noise transmitted through the hull. Tip-clearance is the measurement from the tip of the prop to the hull at its closest point, and it is generally recommended that the clearance should be 15% of the diameter (or more). We were close and wanted to exceed that. With the Southerly it is an issue as well since there is a skeg that protects the prop when the boat is in very shallow water (less than 1 meter!). So planning a new propeller has meant we are in the same situation - trying to fit in that restricted space.
Two-Step has an aperture for the prop

One thing I always wanted for Two-Step was to try a feathering prop – but I wasn't able to find one to fit (they mostly have a longer cone out front that is too long for the aperture between rudder and keel where the prop is). For the new boat I am very excited to find the Variprop that looks like it will solve all problems! It has a short cone so the smaller space isn't an issue and best of all it is available in a four-blade version that offers greater efficiency when you have had to choose a smaller diameter than normal. The actual business of ordering a propellor can seem daunting since there are a lot of questions to be answered. Maximum diameter and clearances around the prop are just the start! Engine horsepower, and transmission ratios are used to calculate diameter and pitch. Shaft diameter, taper and nut dimensions are obviously important to insure the prop just slides on. In the case of the Variprop we will be able to keep the basic prop as a spare since the Variprop will be made with the same dimensions as the original.

One of the best things about a feathering prop is that they are generally adjustable so if you do guess wrong and the pitch is not correct, you can reset it. With a fixed prop you would have to have it expensively re-pitched if it wasn't right. Most of the feathering props let you realign gears or adjust something and set the pitch. In most cases you have to haul the boat out, disassemble the prop and fix it. But the Variprop even allows you to re-pitch it in the water – saving a haul-out.

I only wish we had tried one on Two-Step so we could compare it to the performance of our fixed blade prop. But I will definitely report back on how it goes on the Southerly.