FLYING TIGER 13.8M

[Bob Perry]

Bill called this morning.

He has made the decision that the 13.8 will come standard with a lifting keel.

The keel will be hydraulically raised and powered manually.

I need some ideas for how to make this work, hydraulically. Can anyone out there point me in the right direction?

I learned during the FT10m project that there are a lot of smart guys out there on SA. I need at least one now.

I'd like to keep the entire system as simple as possible.

This will increase the cost of the boat but it will also open the boat up to a lot of sailors with draft issues.

Again, it will be standard on the 13.8.

I thought it was going to be a quiet Sunday, do some fishing, watch some golf, wash the wife's car but no.

 

[nroose]

Well, I don't know how to solve the problem, but I think I know the question that needs to be answered first:

How far does it need to raise up?

 

[Snarley]

From here down there are some ideas.

I am not an Engineer so put this more as a thought than an idea. Because we are dealing with such a large amount of weight would it not make the lifting solution much easier if we used two hydraulic cylinders fore and aft of the keel slot to reduce the weight we need to lift?

Two cylinders with 30" arms that say are rated for 3000lbs a piece. The arms attach to the top of the fin and when extended provide 30" and 6000lbs of lift. The 3000lb (6000 lb total lift) would be continuous and there is no need to be able to vary the lift of the cylinders. This would allow you to reduce the amount of weight you need to lift so as to use a proven solution.

Could this be done? Is there a way to reduce the amount of weight that needs to be lifted and then apply one of the conventional solutions to raise a keel?

My thought is a keel box that extends high enough such that when lowered provides the base for a table. On either end is a hydraulic cylinder. This way it might be possible to build the boat to a standard spec and make all of the lifting gear optional.

 

[Christian]

Bill called this morning.He has made the decision that the 13.8 will come standard with a lifting keel.

The keel will be hydraulically raised and powered manually.

I need some ideas for how to make this work, hydraulically. Can anyone out there point me in the right direction?

I learned during the FT10m project that there are a lot of smart guys out there on SA. I need at least one now.

I'd like to keep the entire system as simple as possible.

This will increase the cost of the boat but it will also open the boat up to a lot of sailors with draft issues.

Again, it will be standard on the 13.8.

I thought it was going to be a quiet Sunday, do some fishing, watch some golf, wash the wife's car but no.

This has been done well by Bill Tripp and a couple of the bigger Thompsons

Think a relatively tall keel trunk with the hyd cylinders built in forward and aft - cylinders stay in the keel trunk and the pistons push up on the bottom of the keel-top-flange. Need to have good solid guides for the keel blade at both the top and bottom of the keel trunk. Also need to have a mechanical lock in the up position to mitigate the risk of a hyd failure. This keeps the weight of the hyd cylinders relatively low.

I would caution against manual power - it is a hell of a workout to raise a heavy keel and a small electric powerpack is not going to be very heavy/costly compared to a manual one. Remember to engineer in safety valves close to the hyd cylinders so a blown hose/pipe doesn't have the keel in freefall.

 

[SCARECROW]

Fabricated keel with the cylinder(s) in the keel and ram facing up (or line bored cast keel) that way you only need the keel box to extend 150mm beyond the top of the retracted fin.

 

[Snarley]

Boat Design forum -Lift Keel

 

[PHM]

Bill called this morning.He has made the decision that the 13.8 will come standard with a lifting keel.

The keel will be hydraulically raised and powered manually.

I need some ideas for how to make this work, hydraulically. Can anyone out there point me in the right direction?

I learned during the FT10m project that there are a lot of smart guys out there on SA. I need at least one now.

I'd like to keep the entire system as simple as possible.

This will increase the cost of the boat but it will also open the boat up to a lot of sailors with draft issues.

Again, it will be standard on the 13.8.

I thought it was going to be a quiet Sunday, do some fishing, watch some golf, wash the wife's car but no.

Bob, this is a great opportunity to develop a good system that could be used on fast cruising boats too. There are so many places that require less than 6' draft throughout the world--it would be great to have a 40'er or 50'er (a monohull--I know a cat is a solution too) that had an uncompromised keel for sailing that could fit into thin water too.

 

[Pavook]

bob, bill,

going with a lifting keel is GREAT. Glad you listened to us. it will definately be well recieved, particulalry at the right price, although i think this feature shoud be an option. Just design it in from the start! keep base cost of boat th same!

Simple hydraulic, or screw jack is likely best. althogh an electic winch with cable can also work and is much more cost effective.

I like the screw jack idea best, as discsussed in other threads. simple effective, can anchor both ends, positive clamp, and much less room for catastrophic failure. and stainless models are available. and driven electrically so no mess with hydraulic fluid. and they can be very very accurate.

agree that the keel trunk should be table top height. I would aso recomend going with a full floor to ceiling enclosed keel box (with access hatches to access keel bolts). it inc reases safety, disperses loads etc. can be integrated as part of wall for head etc. (email me and i would be happy to discuss and send info)

I also think a lifting keel will get alot of use when transporting the boat. raising the keel to lets say 5 feet of draft means you can now put this boat on a trailer (semi truck trailer, not a self tow) without having to disassemble the keel. that is a big big plus.

 

[us7070]

the thought of a cable scares me...

 

[nroose]

Come on guys.

Making it work on cruising boats as well makes it take longer and cost more.

Making it optional makes it take longer and cost more.

 

[Bob Perry]

For now it's enough to concentrate on a simple system that will work on the 13.8. I will work with Ivan on engineering the system but all ideas are very welcome. I will take trunk from the hull to the cabin top. It's the strongest way to do it. For now.

 

[BGD]

Bob - Your friends at Schooner Creek did a lift keel on this 42'er

http://huberman.org/prestissimo/

 

[mvining1]

Bill called this morning.He has made the decision that the 13.8 will come standard with a lifting keel.

The keel will be hydraulically raised and powered manually.

I need some ideas for how to make this work, hydraulically. Can anyone out there point me in the right direction?

I learned during the FT10m project that there are a lot of smart guys out there on SA. I need at least one now.

I'd like to keep the entire system as simple as possible.

This will increase the cost of the boat but it will also open the boat up to a lot of sailors with draft issues.

Again, it will be standard on the 13.8.

I thought it was going to be a quiet Sunday, do some fishing, watch some golf, wash the wife's car but no.

Hooray! One design racing for the masses in 44 footers. What could be more fun?

 

[Christian]

For now it's enough to concentrate on a simple system that will work on the 13.8. I will work with Ivan on engineering the system but all ideas are very welcome. I will take trunk from the hull to the cabin top. It's the strongest way to do it. For now.

If you take the trunk all the way up (which is a good choice if you can fit it into the boat nicely) I would use a spindle system (one front and one aft). Simple engineering, locks the keel in any position, very easy to drive with an electric motor, low maintanence, much cheaper than hydraulic and much more fail safe.

 

[Bob Perry]

Christian:

Thanks. By "spindle" do you mean a worm gear? Are there any current examples of this type of keel mechanism?

 

[GRUMPY]

Bill called this morning.He has made the decision that the 13.8 will come standard with a lifting keel.

The keel will be hydraulically raised and powered manually.

I need some ideas for how to make this work, hydraulically. Can anyone out there point me in the right direction?

I learned during the FT10m project that there are a lot of smart guys out there on SA. I need at least one now.

I'd like to keep the entire system as simple as possible.

This will increase the cost of the boat but it will also open the boat up to a lot of sailors with draft issues.

Again, it will be standard on the 13.8.

I thought it was going to be a quiet Sunday, do some fishing, watch some golf, wash the wife's car but no.

I worked on a big Elliot (52) with a hyd op lifting keel. Funnily enough the job was fixing the keel which had stuck down. Hydraulics issue

 

[Zonker]

Bob,

Maybe talk to Cariboni in Italy. They are hydraulic specialists and have done a lot of BIG lifting keels.

Sometimes its better not to reinvent the wheel.

 

[SCARECROW]

No harm in calling them but I suspect a Cariboni package would eat a lot of the 200K budget.

 

[Christian]

Christian:Thanks. By "spindle" do you mean a worm gear? Are there any current examples of this type of keel mechanism?

Not sure it would be called a worm gear as a worm gear would have the spindle and a gearwheel. Think of a scissor car jack. Obviously you would have the spindle vertical and the "nut" (with internal groves mating to the spindle) connected to the keel top plate and the bottom standing on a bearing in the bottom of the keel trunk Obviously you would couple the two spindles so they turn in unison and it will be very easy to add an electric motor in that loop to drive it. Probably need some safety switches both top and bottom so some moron doesn't drive the keel to far in either direction. I am not sure if there are any current examples of this but is such a simple and bulletproof way of doing it.

 

[bslevin87]

I think what Bob is looking for is at the following link: http://www.danahermotion.com/website/com/e...screw_jacks.php

These jacks can easily lift a 7000 lb keel and each jack with 30 in of travel will way around 70lb. A very good weight for an excellent option.

There are many advantages to using screw or worm jacks. There is a durability advantage and safety advantages. You can physically lock the gear from turning preventing the keel from moving up or down. As the keel is raised or lowered a spring loaded pin or similar device locks the keel in that position. When you need to move the keel position the pin or similar device must be pulled out to allow the keel to move. You could also use extra keel bolts to secure the the keel when racing offshore. The worm gears can also be turned by electric motors, which can easily be powered by a genset which there has been a rumor floating around will be part of the propulsion system.

I think using hydraulic jacks or a wire pulley system here is not a good solution. Mechanical jacks provide safety features, reliability and can be powered electrically.

Lets iron out this system for Bob so let the questions fly.