Keel mechanism

[Suomeksi]
Guyline 95 is exceptional because of its keel that can be tilted hydraulically. It is pretty rare design at least here in Finland, only Guylines and very few other sailboats have tilting keel, probably because it is more expensive to build.  If you think about sailboat keels in common they have two main functions, they are meant to prevent drifting and heeling. Heeling or tilting is prevented by keels weight that why keels are often made of lead, while drifting is prevented by keels length and wing kind of shape. So when wind blows to sails, sails change air motion such a way that it creates forward moving force to boat, but in same time it also pushes boat sideways causing boat to drift with a wind. Run wind is of course exception, but you can't always run with the wind ;-). Because boat is moving ahead, keel acts kind of like a wing and prevents or at least reduces drifting with the wind. Basically longer the keel better it prevents drifting. Keels length (depth) is more significant than its width (or length in boats direction). One might think that big wide keel would prevent drifting better, but that is not the case, the force depends on amount of water passing by the keel and it is same no matter how wide the keel is. Most optimal keel would bee very narrow but same time very long.

Keel up and down

Keel in Guyline is designed so that it tilts backwards so that draft can be reduced when necessary. In above picture you see how keel tilts. When hydraulic oil is pumped to cylinder, it pushes keel back and up. Cylinder body is attached to boat and cylinder rod is attached to keel. Guyline has pretty big draft (2.4 m) for this size of boat when keel is down but it is reduced to 1.4 meter when keel is tilted up which is quite small in comparison. Smaller draft is of course very useful in shallow waters and it enables one to visit some harbors and shores that would otherwise be out of reach, but it is also useful if you accidentally hit sea bed, most cases it lets keel tilt back rather than cause serious damage to the boat.

Cylinder

Cross-section of the cylinder

Cylinder is made out of stainless steel so it could withstand corrosive effect of sea water. It is as shown in above picture, pretty simple single acting cylinder. Rod is pushed out when oil is pumped to cylinder and when pressure is released, keel pushes rod back in. There is little safety mechanism (orange) right before hose that reduces oil flow out from the cylinder so that keel will never go down too fast even if hose breaks. There is seal in front of the cylinder (green) that is hold in place by locking ring (red). Cylinder rod has own locking ring (blue) that prevents rod coming out. If cylinder rod needs fixing, cylinder must be cut open to get rod out. Then it must be welded to put it back together.

Cylinder taken out of boat

As far as I know cylinder does not have any specific brand. It has been custom made by some hydraulic workshop for these boats. While you may not be able do much to it by yourself, any well equipped  hydraulic workshop can fix it and even create brand new cylinder for you if needed. So no need to worry about that. Seal of the rod is weakest point of the Cylinder and when it wears out, and starts to leak oil, you need to take cylinder out and get it fixed. It is easy to imagine that seal might fail if rod gets lots of sea growth on it especially barnacles. If you don't get it fixed, it may affect cylinder rod, by scratching it. Worst that can happen is that water gets inside cylinder and when it freezes during winter, it breaks or distorts cylinder body. But normally cylinder is not something that you need to take care of very often. Mine had not been maintained ever, so it had worked at least three decades.
I decided to take my cylinder out for maintenance, because previous owners  had never done it. Seals for the shaft are not very expensive, but when I took it to hydraulic workshop, they recommended to make new hard coating for rod. Hard coating itself is pretty expensive compared to just changing seal and to get rod hard coated, they needed to cut cylinder open so it costed way more (about 450€) than I originally thought. But it is now fixed and good as new, so it will probably last for couple of decades again. Because cylinder was out, I decided to get new hose too. Old hose didn't seem to be in very bad shape, but I have heard that they have failed some times, so better be safe that sorry.
To keep cylinder in best condition, you should keep keel down whenever possible. When keel is up, cylinder rod is out and exposed to seawater, sea growth and if rod gathers much sea growth, especially barnacles, they will break rod seal.

Detaching Cylinder

Cylinder can be taken away from above, in fact it is only way, if you don't detach whole keel and lift boat up. Of course boat must be on dry land when you take cylinder away. There is little square hole on boats floor that is covered by stainless steel plate. There are two sizes of holes. In older boats like mine, there is smaller hole and only little cavity where hose can go. And in newer boats hole is longer and whole pumping mechanism is fitten in the cavity. In newer boats cylinder is little bit easier to lift trough the hole, because hole is longer, while in older boats cylinder rod must be pressed in before cylinder can be tilted enough up and trough the hole. On the other hand newer boats have also longer stainless steel plate with more bolts and glue to be removed before it can be taken away.

Hole cover detached

To detach cover, you need to unscrew nuts (the easy part) and then somehow separate glue. If gluing is well done and there is enough thickness in glue, you can use some sharp blade to cut trough the glue. But if that does not work, you might use some combination of chisels, flat screwdrivers, thin blade and hammer. For example you can use screwdrivers to lift cover just little bit so you can fit blade under and cut the glue. Anyway take some time and be careful not to brake boats surface or bolts. Make sure you clean all surfaces well before putting all back together.

 

Before cylinder can be taken away, it must be separated from keel and boat. There are two big pins in both ends of the cylinder. Pins can only be taken out from ouside of the boat. There are little discs at end of the pins that hold them in place. Discs are hold in place by two little bolts. Pins should come out pretty easily, they shouldn't be too tight. If they are tight, there might be pressure in cylinder or boat is resting on the keel so that it pulls cylinder.After pins are removed, you must press cylinder rod inside so that cylinder can be twisted up. It is not easy to push rod back in when cylinder is in place. I used some wooden stick as lever, but if you have some kind of pumpu, you might be able to suck oil from cylinder, so that rod retracts itself. It would be easier to take cylinder out if keel was down, but it would require higher stand for boat and that might not be available.

Putting cylinder back in place

Putting cylinder back in is easier, because you can easily push cylinder rod in and then use cylinders own pump to get rod out when cylinder is in place. But putting pins in place is little trickier. When cylinder is put in place and it rests on keel, it is little lower than when it is in correct place. In other words, it must be lifted up little bit so that pin holes can be aligned . Front of the cylinder is easy to lift on correct height from inside of the boat, but you can't really lift back of the cylinder from inside. Luckily there is little hole in the keel (see picture) where you can push cylinder up with a screw driver or some other tool. Hole might be full of dirt and even painted over, but it should be there.

Rear end pin and hole that can be used to lift cylinder rod to correct height

After you get cylinder in place and all the nuts and bolts are tightened,  you might think how do I bleed air out of this system? Well you don't really need to worry about it. You just fill pumps oil reservoir with oil and pump it to cylinder. After first pump there will be oil and air in cylinder, but since air is lighter, it will go up and get out first when keel is lowered. Not all air will come out at first, but you then pump keel up and let it go down few times and all air should get out just fine.

Pumping mechanism

Pump for keel hydraulic

Pumping mechanism is quite simple and robust. In this model lever is turned up and down and it pumps oil in both strokes. Pump is branded as Dowty and same design seems to be available nowadays from Indian J&G company  in many different brands. I don't think this pump will ever break or wear out totally, but if you need to replace it, it is good to know that there are still still brand new ones available. Pump is attached to oil reservoir, that is probably custom made. It is made from steel and then painted well. There is manometer in pressure line that will show how much pressure is in line and you can use it to estimate how up keel is. When you start to pump keel up, manometer shows something like 100 Bars and when keel is almost up, pressure shows something between 120 and 140 bars. When keel hits top, pressure rises quickly above 130 Bar, because cylinder rod can't go any further and thus oil has nowhere to expand. You can easily feel it when pumping. After manometer the line is forked in two branches, one goes to cylinder and other directly back to oil reservoir. There is check valve preventing oil going back to reservoir. It is designed so that oil gets easily from oil reservoir to cylinder if keel hits some obstacle. If cylinder could not get oil in this situation, it would develop vacuum in cylinder and that is not good for seals. Also all extra resistance from impact would be transferred to boats hull.

Maintaining pump

There is not much, you need or even can do to maintain this pump. There are no seals inside the pump that you could change. I don't know if pistons or any other parts are even available as separate. If pump does not work, you should check the safety valve. It is located inside the oil reservoir and attached beneath the pump. It looks like bolt that has little hole trough it (see picture).  My pump had problem that it didn't produce enough pressure and it could not lift keel all the way up, it resulted from safety valve. Safety valve releases oil back to reservoir if pressure gets too great. There is little screw on top of the safety valve that adjusts tension of the spring and it was too loose. I opened whole valve, cleaned all parts and put it back together. I have no tools to test spring tension, so I just tightened it approximately. It ended up working after that. So it was easy cheap fix.

Safety valve