| Author |
Message |
    
gregoryan
Member
Username: gregoryan
Post Number: 29
Registered: 09-2004
| | Posted on Tuesday, January 06, 2009 - 10:01 pm: | 
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Once owned by Qantas in association with their Catalina flying boat service out of Rose Bay Sydney Australia, [1940's]
This Boat; powered by a 10HP Blaxland Chapman Sea Dog [Two stroke 4.75"x 4.75" = 1380cc. 700RPM]
pic taken in 2005, its name then was Freya, anchored at Phegans Bay NSW AU. [not there now]
Note the magneto bracket as a size ref, as it is the same casting as used on the 3.5Hp. but is mounted on the crankcase/ not the waterjacket. Note that the [ 1.25inch air intake] carburettor size/ against the magneto size! The crankcase also has inspection covers. There is no primer bottle in the holder.
18" flywheel, bounce-start only, no pulling over compression via strap and your back!
Same waterpump body as 3.5HP but with 1" stroke rather than 3/4".
Note the window in the skirt; this aligns with the lower end of the transfer/ scavenge duct.
note the strange tall crown!, any comments?
the aerosol can is for a size reference |
Brandon P
Visitor
| | Posted on Thursday, January 08, 2009 - 01:05 pm: |
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Is the tall crown to increase compression? The 1920's Super ELTO twin outboards have very similar pistons in shape/crown/scavenging duct. Oddly, they are bounce start only as well, even though they are a very small engine. If compression is higher via a crown, does that make it less difficult to start on a bounce than others; or is it just a way of making room for the port while putting some "beef" on top? |
gregoryan
Member
Username: gregoryan
Post Number: 30
Registered: 09-2004
| | Posted on Friday, January 09, 2009 - 05:31 pm: |
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Amazingly; I was sent some more pics of the same boat that Neil Jones took a couple years earlier!
shame the engine box was on!
 |
gregoryan
Advanced Member
Username: gregoryan
Post Number: 31
Registered: 09-2004
| | Posted on Friday, January 09, 2009 - 05:49 pm: |
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Brandon; yes that makes sense; Is the tall crown to increase compression? If compression is higher via a crown, does that make it less difficult to start on a bounce than others; or is it just a way of making room for the port while putting some "beef" on top?
Yes; if the height of the transfer deflector is on the piston anyway, then there is going to be a large low-compression combustion-chamber unless its filled by something,[ other than a wierd chamber roof shape, which would upset the cross-flow gasses]
As for a better bounce start; being that it is sparking on only half a compression stroke, you'd imagine more compression would help! Thanks for your input! |
gregoryan
Senior Member
Username: gregoryan
Post Number: 75
Registered: 09-2004
| | Posted on Monday, January 17, 2011 - 07:23 pm: |
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 email me if you want the full enlargeable file size of these pics. It was hard to resize to under 200kb to upload here |
senojn
Senior Member
Username: senojn
Post Number: 71
Registered: 08-2006
| | Posted on Wednesday, January 19, 2011 - 01:54 am: |
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I didn't mention at the time but I was looking to buy this vessel .Price was good but draft a little too much for my mooring and location .
As you can see from the first photo the boat was sitting at low tide .The second picture I took didn't show the beautiful 'Sea Dog' because if you look closely the craft was full of water ,still draining and the motor cover was floating . |
johnoxley
Member
Username: johnoxley
Post Number: 13
Registered: 04-2010
| | Posted on Wednesday, January 19, 2011 - 05:13 am: |
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Hi - extension to piston crown will be a scavenging deflector to cause incoming transfer charge to travel up, over and down towards the exhaust port. Many earlier two strokes (including Evinrude) are like this. Later two strokes have two or more transfer ports at the side and a flatter piston for loop scavenge. Deflector pistons are usually significantly heavier |
gregoryan
Senior Member
Username: gregoryan
Post Number: 77
Registered: 09-2004
| | Posted on Wednesday, January 19, 2011 - 04:29 pm: |
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Sea Dog Search-result............
Timor
Harry White was posted on 11 October 1945 to probably the smallest Marine Section Unit in the RAAF located at Koepang. Harry and a Fitter/Engineer had a very small boat
eighteen feet in length powered by a 10 HP Chapman Sea Dog engine. Each day a Catalina
arrived with supplies and after the Crew spent two hours ashore they were ferried back to the
Cat. This two hour daily duty by the two Marine Section continued for a four week period.
Again, ingenuity and initiative by two Australians probably sustained them during their time
at Koepang.
A posting duly arrived, so after loading their boat on a Landing Barge they were taken
in tow by a RAN Corvette for the long trip back to Darwin. Harry, the Fitter/Engineer and
another chap remained on the Landing Barge until they reached East Arm RAAF Base.
...................
from; http://www.futurepd.org/les/Documents/NewBook%20G.pdf} |
gregoryan
Senior Member
Username: gregoryan
Post Number: 99
Registered: 09-2004
| | Posted on Wednesday, May 16, 2012 - 10:17 pm: |
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And; So it comes to pass, that the Sea Dog in the above pictures is now for sale [without the boat] The engine is complete but in parts. Please write if interested so that i can send you the details, components pictures, location and contact. |
