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fcrammond

Bowman Launch speed trials at APS.

The need to set up and fill the pool for the recent “A Day At The Seaside” steam day gave me the opportunity to make a few reasonably accurate measurements of Bowman steam launches under way. Before the pool was filled I fixed two cross markers 25 feet apart on the bottom. With a roughly 36 foot long pool this gave a few feet either end for acceleration and stopping. Filling the pool on the Friday gave me all Saturday to play steamboats as for the Sunday event the pool was devoted to the sort of toy sailing boats so very familiar to us older children on seaside holidays (Star, Bowman etc.)

In the event time seemed to slip by but I managed to run and measure examples of the four Dereham built Bowmans and also a post-war Luton Seahawk as well as a modern fibreglass launch powered by a Mamod ME1 with vapourising burner. Several measurements were made in both directions and both the best figures and the average are listed below.

Boat fastest time average time average speed(fps)

Milvus 15.7 16.0 1.56

Eagle 19.5 21.3 1.17

Seahawk 16.0 17.1 1.46

Snipe 15.0 15.7 1.59

Swallow 16.4 19.3 1.30

Luton Seahawk 16.8 18.8 1.33

Conditions were warm with very little wind. Times are in seconds.

I do not claim these figures to be definitive but merely a beginning. I am sure the state of the burner, the safety valve and engine itself are all significant and the general condition of the boat in terms of temperature and lubrication plays a part. It will be interesting to acquire data on more individual boats to see how much variation occurs. Meanwhile I need to test the rest of the fleet when the opportunity is there. Sadly, setting up and dismantling the pool is a two day job, not to mention filling it with water so it is not a job to tackle lightly.

The Mamod engined boat mentioned above is Milvus aka Emma.

Spokesmann · Posted: Thu Sep 17, 2009 4:28 pm Post subject:

Great stuff, sadly I missed this, overall things look pretty close!, although the eagle due to its size and complexity seems a little slower. Make me wonder how my Arrows will do...
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John Chapman · Posted: Thu Sep 17, 2009 5:27 pm Post subject:

Very interesting Fred, thanks for sharing the results with us.
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Phantom · Minor 1 - beginner : Joined: 03 Jun 2008 Posts: 141

Interesting comparing Eagles performance against that of Sea Hawk.
Both use the same hull. Eagle is perhaps slower becouse of only having a single cylinder engine compared to Sea Hawks twin cylinder engine.

newts · Posted: Thu Sep 17, 2009 6:49 pm Post subject:

GO the snipe Mexican wave

Interesting stuff Fred.
Not much difference in the speeds overall, only the Eagle really lagging behind.
Hope the Snipe didn't take a pecuniary advantage, with the aid of vaseline below the waterline Question

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MFSteam · Posted: Thu Sep 17, 2009 9:40 pm Post subject:

Interesting Very Happy

A weekend with Lord Montigue prevented me coming but the Champion Swallow will take a trip up to STIA to show you how it is done q27

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www.mfsteam.com the home of the MFTwin and replacement parts for Mamod, Bowman, Hobbies and Cyldon Steam Engines

Spokesmann · Posted: Fri Sep 18, 2009 7:31 am Post subject:

MFSteam · Posted: Fri Sep 18, 2009 8:24 am Post subject:

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