The Unofficial Mamod and Other Steam Forum

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.

Roly Williams · Posted: Thu Sep 17, 2009 6:51 pm Post subject:

Hmm. Interesting. It would be good to see what the variation is between examples of each model. I.E. are the differences mainly due to design or to condition?
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Roly Williams

"God is not dead - he is alive and well and working on a much less ambitious project" (MRFS)

logoman · Posted: Thu Sep 17, 2009 8:09 pm Post subject:

I was dissapointed that I couldn't make it to 'A day at the seaside'.

fcrammond · Posted: Fri Sep 18, 2009 4:33 pm Post subject:

You didn't miss much steamwise. I spent the day supervising hordes of small persons who were sailing Star Yachts and so on. Nearly lost several eyes to the rear end of boathooks

Most of the steam trials took place on the Saturday.

I hope to do it again before STIA but am usually V Busy on the Saturday.

Fred

mogogear · Posted: Fri Sep 18, 2009 5:46 pm Post subject:

The Snipe did us all proud - what a speed demon !!

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Mo

This week I are His Most Noble Lord Mo, the Apocalyptic of Old Tonbridge Wafers