Search found 1069 matches

by barts
Sat Nov 12, 2011 9:17 pm
Forum: Members' Websites and Boats
Topic: Next Weekend II
Replies: 162
Views: 177329

Re: Next Weekend II

Wow - neat! You guys are making progress! For a condensing compound, you can basically assume 30-35 BMEP on the big cylinder depending on 150-225 psi steam pressure... so that engine w/ a 10"x6" can produce 33 * .5 * 78.5 * 400 /33000 or about 15 HP at 200 rpm. That boiler will produce enough steam ...
by barts
Sun Nov 06, 2011 2:01 am
Forum: Technical - non Engines and Boilers
Topic: Clutch options
Replies: 19
Views: 18434

Re: Clutch options

My boat is the one that Bart mentioned with the monotube and clutch. It is I believe what many people would call a "dog" clutch. I will see if I have any pictures, as the boat is in winter storage now... Dog clutches: http://en.wikipedia.org/wiki/Dog_clutch You have a multiplate clutch, I think. - ...
by barts
Sat Nov 05, 2011 3:38 pm
Forum: Technical - Engines and Boilers
Topic: Feedwater pre-heating with a hotwell and vacuum pump
Replies: 16
Views: 15180

Re: Feedwater pre-heating with a hotwell and vacuum pump

What I do with the Otter to introduce make up water is to switch the pump suction from the hot well to the makeup tank. This causes the hotwell to start filling immediately; if I forget to switch it back the hotwell spilling over on my leg reminds me :). If I used a vacuum pump I'd likely just use a...
by barts
Sat Nov 05, 2011 3:25 pm
Forum: Technical - non Engines and Boilers
Topic: Coefficient of linear thermal expansion
Replies: 2
Views: 4467

Re: Coefficient of linear thermal expansion

Note that the impact of this difference is quite small for hobby scale steamboats, and most of the parts that are working in close proximity (such that the small size change could be important) are subject to roughly the same temperatures..... Any design where this was critical would probably be muc...
by barts
Wed Nov 02, 2011 10:13 pm
Forum: Technical - Engines and Boilers
Topic: Feedwater pre-heating with a hotwell and vacuum pump
Replies: 16
Views: 15180

Re: Feedwater pre-heating with a hotwell and vacuum pump

I would use the vacuum pump to pull the condensate from the condenser into the hotwell. The feedwater heater should come after the feedwater pump; otherwise the hotwell can get too hot and the pump won't pump hot water (vapor lock). The float valve bypass just returns the water from after the pump a...
by barts
Wed Nov 02, 2011 2:30 am
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 8247

Re: Mean Effective Pressure calculations

Also note the great economy (even when exhausting to the atmosphere, 15 psia) at say 65% cutoff: MEP Factor = (0.9300 x 115) - 15 = 91.95 MEP. 35% less steam by volume for a pressure decrease of only 8.05 psi. This works well... but keep in mind that the more expansion is done, the bigger the impac...
by barts
Tue Nov 01, 2011 3:19 am
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 8247

Re: Mean Effective Pressure calculations

I think the relationship you're using for expansion of steam is wrong for adiabatic expansion. Bart: You are correct. I'm assuming isothermal expansion, which is the relationship I've found in two books so far (at least for the initial rough estimates at the very theoretical level). . Isothermal (c...
by barts
Mon Oct 31, 2011 4:02 am
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 8247

Re: Mean Effective Pressure calculations

I think the relationship you're using for expansion of steam is wrong for adiabatic expansion.
Compare your estimate with values from a steam table.

- Bart
by barts
Sat Oct 29, 2011 8:04 pm
Forum: Technical - non Engines and Boilers
Topic: Bronze for bright work
Replies: 8
Views: 9377

Re: Bronze for bright work

Put me on your "buyer" list as I've been looking and haven't been able to find 6" cleats...I need four. The shiny polished ones with some sort of varnish don't fit the character of our boat. I've been happy w/ the Herreshoff bronze cleats; very traditional, and they weather to a nice color. I found...
by barts
Fri Oct 28, 2011 4:58 am
Forum: Technical - non Engines and Boilers
Topic: propeller
Replies: 6
Views: 6916

Re: propeller

The larger the prop diameter, the lower the slip... ideally, for a displacement hull you'd like about 1:1 ratio of diameter to pitch, since that ratio is most efficient. This is hard to fit under a lot of hulls as the pitch is more or less determined by RPM; most steamboats end up running a lot more...