bilge keels

[roxanne parola]

Ok I know it isn't REALLY a sailboat, but it's more like a sailboat than a powerboat; it's a steamboat. The hull design is a Weston Farmer one and it is 25ft loa with a completely round bottom, just a stub of a keel; about half a foot. Displacement hull, top speed is about 8 knots. This thing is TENDER only about 7 feet wide, I don't know at the water line and it rolls like crazy, especially with a vertical boiler it's also top heavy. What about bilge keels?, would they help the rolling? How about materials?, the hull is a cold molded wood one about 1 and one half inch thick, can I just bolt an aluminum flange to it? Any thoughts would be helpful. Thanks Ron Parola

[cyclops]

A top heavy boat, that has a steam pressure boiler.-----Do you know what can happen when a "up to pressure " boiler is rolled over into cold water? Your odds are 50/50.

[D'ARTOIS]

Of course a double bilge keel would dampen the rolling, or suppress it's tendency, but with a top heavy boa you have to be indeed carful, as cyclops remarks, you might be in a bad shape when she capsizes.
I feel that she is one of those Gentlemen's steamlaunches that cruise the Thames - they are operated in quite waters where waves are insignificant.

[cyclops]

Kind of like the one in Sherlock Holmes chasing Professor Moriarty down the Thames? Neat! Putting 2 heavy metal keels on the bottom would help if you still have enough freeboard height above the water.

[Bergalia]

Cyclops is correct - in its present state it sounds as though you are 'sailing' an unexploded bomb.
And D'Artois appears to be on the right track. Was she designed to carry a vertical boiler (as in a Thames steam runabout) - or is it something you have added. If so, flat calm is definately order of the day.
For choppy conditions a couple of solutions are possible - both require a fair bit of heavy surgery.
(a) install a horizontal boiler (but keep your upright stack) plus lots of inboard balast; or
(b) a heavy dagger keel - to lower the centre of balance. On a Thames runabout you would need something like 1 - 1.5 ton at about 1 - 1.5 metres below the waterline.
Won't look pretty when beached - but better than being scattered across the horizon.
By the by, I've no objection to steam - tremendous traction power. As a boy crewed for my dad on a steam trawler; triple piston Fowler engine. Left the 'new' diesel boys standing.

[cyclops]

Steam has maximum torque availabe at 0 rpm's. Only other engine close is a controlled waste gated, geared down turbine.

[roxanne parola]

Yes I do know what can happen with hot steam and cold water!!!! But This boat has been sailing around since '81 and we haven't rolled yet, I'm trying to keep it that way. Yes it is an English launch and we only go out in protected waters and calm days and also the boiler is original. Can you just through bolt a set of keels on? or would there be too much localized stress?, since there are no ribs just a hull to fasten to. Thanks RP

[cyclops]

I am taking a car home.

[Bergalia]

Originally Posted by cyclops

I am taking a car home.

Come back here, Cyclops - we need your experience. What do you reckon ? Fit some ribs or bulkheads to take the strain of a new keel ?

[yokebutt]

Rox,

How about a daggerboard? I'd suspect damping would be a square function of draft, (or extension of the blade, to be more precise) so a single deep blade might have a better effect.

Yoke.

Yoke.

[marshmat]

You'd probably get best stability with a single deep board as Yoke suggests. Your bilge keel idea would probably help quite a bit. If you're sticking to calm waters, I would through-bolt with a large metal backing plate. You could also add some ribs to help spread the load, this would probably be a stronger way to go (esp. if you have big waves to contend with) but would involve more work. You would still want metal backing plates on the bolts.

[Wynand N]

Originally Posted by cyclops

Steam has maximum torque availabe at 0 rpm's. Only other engine close is a controlled waste gated, geared down turbine.

Electric motors also have max torque available from 0 upwards rpm......

[cyclops]

True. Some classes do. They are very rarely used except on the constant tension support cables of USN oil tankers and USN supply ships. 1 other that I know of is almost all the large cranes at big container ship piers. The starting currents are by application " unlimited ". I had the opportunity to rebuild 3 units for the Port of Newark, NJ.

[roxanne parola]

Another thought; since our little stub of a keel is about 3.5 inches wide and obiviously the length of the boat what about a strip of metal that width & length egualing 500 or so pounds? I am leary about a deeper keel (dagger board etc.) since we tow it around alot, and run in shallow waters often, just hit a tree this weekend in Lake Sonoma in fact, ripped a condenser mount off , Rats Cheers RP

[cyclops]

Since you have not blown it up since 1981 and more damage is done by the trees growing in the river. Don't sweat the keel.