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[Muleears]

I have determined that my PMR 8M and Maccsteam 3.5" 750ml boiler is too large for my 70cm African Queen.  So I don't do this again, is there a rule of thumb that will help me determine what size motor a particular boat needs?  I realize the boiler is determined by the motor size, but is there any guidelines for that either?  I my case I am told the motor/boiler combination is ok, it's just physically too big for the boat.  Any input is appreciated.

[Underpressure]

You have sort of hit the nail on the head with your final words: If it won't physically fit in the model, it is too big. For a 700mm long model, I would look at the Macsteam 2.5" boiler and an engine along the lines of the Cheddar Pintail, or one of the SVS twin oscillators (there are a few other alternatives).

Judging what size engine / boiler combination suits which model is really a matter of experience, which is where forums like this come in so handy 

[steamboatmodel]

Malcolm Beak did an article called "Matching engine, boiler and prop sizes" I think it was in Model Boats Magazine originally it is in the download section of Paddleducks. There was also a bit of discussion on props here under TRV1A Prop size. There was another thread on using the Metcalf Mouldings Solent Hull under Steam Launch. I am working on a Diana Steam launch http://www.hartmanmodelboats.com/HMBDIANA.htm which at 50" x 13" would be suitable.
Regards,
Gerald.

[HS93 (RIP)]

If you look at the cheddar Clair, I think that may be about the same size it sails well so if you where to match the plant , as Ian says a pintail and a simmilar boiler to the Clair would work well.

just noticed the clair was a bit biger but hear is a list that Cheddar put out if you have problem reading it ill email it to you full size
Peter

[HS93 (RIP)]

what you need is a mini vap setup for that size of boat.

Peter

[Muleears]

what you need is a mini vap setup for that size of boat.

Peter

What is a mini vap?

[derekwarner]

Muleears ...steam boiler & engines are expensive treasures   ....so one consideration is to increase the size/scale of your hull...if your current hull is 700 mm long you could look at doubling the hull length to 1400 mm

Scale it out on some large paper with a plan & elevation & end elevation ... .......this will allow you to position the  PMR 8M and Maccsteam 3.5" 750ml boiler onto the views....the if suitable draw the footprint's in the plan view & elevation images in the elevation views as reference

You will be surprised at the internal volume increase  & after a 1400 mm long hull is not huge......... & a new larger hull will be more cost effective & display the beautiful steam components in that larger open launch

Good luck   & keep us posted with progress & photograph's........Derek

[HS93 (RIP)]

It was a class of boat brought out for boats aof a certain size a few manifactures built plants to conform, http://www.kingstonmouldings.com/pdministeam.htm

[frazer heslop]

Hi MULE Ears,HS93 beat me to it Kingstones site is well worth a look at they also have a new Queen moulding.A Cheddar Pintail should be a good plant for you're hull.
best wishes Frazer

[Muleears]

Thanks again, gentlemen.  You have given me much to think about. 

Could I use the 8M in the 'Queen I have with a smaller boiler, one that fit?  As Derek pointed out, these are expensive, I need to be buying gifts for others now not me!

I suppose I should try to shoehorn the boiler in the hull, I haven't even test fit it there yet.  I have a garden tub in the master bath perfect for such things.

[derekwarner]

Muleears ....the Macsteam WEB pages have a simple boiler steam capacity requirement calculation ......relative to you engine bore & stroke & hence consumption & running time etc

This eliminates costly guestimations that are only proven or disproven with hot steamy commissiong trials... ......let us know how you get on....... .....Derek

[Underpressure]

Thanks again, gentlemen.  You have given me much to think about. 

Could I use the 8M in the 'Queen I have with a smaller boiler, one that fit?  As Derek pointed out, these are expensive, I need to be buying gifts for others now not me!

I suppose I should try to shoehorn the boiler in the hull, I haven't even test fit it there yet.  I have a garden tub in the master bath perfect for such things.

Your problem then is one of capacity. The 8M is quite a big engine and requires a lot of steam, so matching it to a smaller vertical boiler would be rather like having the V8 engine in your car, but with a gallon can for the fuel tank.

If you already have the boiler and engine, and let's face it, they are the pricey items, then I would seriously think about a different hull / model.

[kiwimodeller]

Muleears, The boiler and engine combination would be fine in a hull around 1metre to 1.4metres, depending on design. The difference will be whether it is a long slim, easily driven hull such as a Wndermere Launch or a shorter, broader beamed hull such as a tug. My suggestion would be one of the Kingston Windermere launches or their Steam Yacht Tender which I know from experience goes very well with the 8M. When you have this one sorted then you can start looking for a smaller engine such as the SVS or a Graham single with a vertical boiler for the Queen. Now you have the perfect excuse for a second steam boat! Follow that up with a paddler, then perhaps a tug and you will be beginning to ammass the experience needed to build a full fleet of steam powered boats. You will be learning all the time, maybe selling one or two off as others take your fancy and you will have a hobby that keeps you occupied for years to come. Good luck and dont forget to post your efforts on here, warts and all - I much prefer to learn from other peoples experiences rather than go through it all myself. Cheers, Ian.

[Muleears]

As always, thanks for the advice.   
Ian, you make a good argument for a different boat.  I like the kingston Windemere launch but I am afraid my building skills (and time) don't allow for a scratchbuild.  I would need a kit (like the Queen).  Have you any other suggestions for a kitted boat?

[frazer heslop]

Hi Muleears,The Kingston hull is a moulding just like the Queen the only slight prob maybe finding materials to finish it.
best wishes Frazer

[Underpressure]

Hi Muleears,The Kingston hull is a moulding just like the Queen the only slight prob maybe finding materials to finish it.
best wishes Frazer

Take a look at the Krick Borkum. There are a couple of build threads on here. Also Deans Marine Victoria and Albert, it might be a little on the small side for the amount of power the engine will produce, but you could fit it all in and you would get good running time.

[Muleears]

I think I have solved my problem.  As another Christmas gift to my self, I have ordered a Krick Victoria. At 46" surely this launch will have enough room for my engine/boiler combination.  After its arrival I will probably start another thread on the build.  Not that I am undertaking a professional level build mind you, I most certainly am not.  I will be asking more questions.  I currently have the building instructions from MiniSteam (where I got the kit).  In other posts I have found that these instructions only address the installation of two different motors, mine is not one of them, so I will need some help there.  I am looking forward to the build and the assistance I will get here.  Thanks to all and Happy New Year!