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[Engineman]

Hi Ian,

Many thanks for such a comprehensive response to my comments  . Nevertheless there are still some points I wish to clarify.

Yes, you are quite right about the hull. Although it matches the Armstrong drawings better than any of the other Ant class gunboats, that is why I chose Mastiff as the one to build.
Understood, but my question was more related to the reason-why you have decided to use the hull from MBD rather than to build it from scratch? The deck outline of the bow part is looking quite like a disaster...

The props are only a temporary fit, commercial 4 bladed jobs, just for testing.
I have already made the correct pattern three bladed ones.
That sounds interesting while having in mind that HMS MASTIFF is a 'first generation' or 'true' flat iron gunboat of 1871 and during these times 3-bladed props were not too much in use...2 or 4-bladed Griffith's propellors with a ball boss were the standard element of the propulsion system for the ships of the era.   
Are these 3-bladed props could be considered like one of the specific features exactly of HMS MASTIFF?
To 'complete' with the propulsion system I want to add that the prop shafts typically had a casing of conical shape (so-called 'trousers'), and I guess that all of the Rendel twin-shafted gunboats did 'wear' these 'trousers' on the propshafts. What about MASTIFF? 
 
As for the rudder blade that has already been corrected, with the more rounded convex curve to the top edge of the rudder. I have found more info since those photo's were taken!
My concern was more related not even to the shape of the rudder blade but to its the overall design (i.e. number of hinges - which is looking excessive, material of the rudder blade, thickness of the blade profile etc). My opinion on the matter (which is based on the plans and photos of the flat iron gunboats and their successors) - is that the rudder blade was wooden and with two hinges only...

There was quite a variation, to the lines and fitting out to the ant class gunboats, as they were all built by different yards to pre set dimensions.
Absolutely true, but I also want to point out that despite these differences in some details - the general design of the boats was pretty similar. Riveted constructions are looking very nice, but I have a serious dout that the engine room skylight as well as booby-hatches and different housings on the deck were made of iron/steel - even for HMS MASTIFF.
These (like the rudder blade) were wooden...
 
You know my perfectionism combined with attention to details sometimes is looking pretty annoying   
 
 
Kind regards,
Roman

[derekwarner]

Engineman.......welcome back ........I remember your engine build from 2006........was it ever completed?....

However I do not want to pinch this build thread........Derek

[Engineman]

Engineman.......welcome back

Hi Derek  . Thanks for your welcome, thou I did not abandon MBM forum thru all these years.
Yep, a lot had been changed since this post of mine from 2006, and the prototype engine is not fully completed yet... By the way - how is your progress with PS Decoy? 
Not to interrupt the thread - there is my small contribution to this very interesting topic related to Rendel gundoats - in general, and probably the best model of 'flat iron' I've ever seen - in particular.

[derekwarner]

Engineman.....this is very interesting 

From your drawings.....it appears that the cannon was retracted then lowered on bottle screw jacks to below deck level ....& only elevated for firing?

[PS Decoy hull was never completed as it is too small form my engine/boiler plant......another day will see a larger hull of PS Adelaide]

Derek

[Engineman]

Derek, you know - it is not my drawing...    it is the drawing from the engineering magazine relevant to the days when the first 'flat iron' was built.
Yes, the gun was stowed below the deck to be elevated for firing only... and it seems that no hydraulic devices were available - since the gunboat itself was relatively small. Probably - there was a small steam engine which used both for capstan 'needs' and for elevating mechanism...
The first Rendel gunboat (as well as some of her other later versions) had no any mechanism for horizontal aiming of the gun...this could be done only by the helm or by the anchor ropes - once the boat was anchored. This fact was already mentioned in one of Ian's posts above.