Antidote to Cabin Fever?
- fredrosse
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Re: Antidote to Cabin Fever?
"Would there be enough clearance for a 12x12 prop?"
The software I have indicated the 12 x 12 prop (300mm x 300mm) at 500 RPM as approximately ideal, but the actual hull configuration is much more suited to a 9 or 10 inch (225 - 250mm) prop diameter, about 80% of the ideal diameter. No big sacrifice in efficiency with this smaller prop, maybe a few % higher RPM could be used. Difficult to go much further in details without the actual lines of the boat.
The software I have indicated the 12 x 12 prop (300mm x 300mm) at 500 RPM as approximately ideal, but the actual hull configuration is much more suited to a 9 or 10 inch (225 - 250mm) prop diameter, about 80% of the ideal diameter. No big sacrifice in efficiency with this smaller prop, maybe a few % higher RPM could be used. Difficult to go much further in details without the actual lines of the boat.
- PeteThePen1
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Re: Antidote to Cabin Fever?
Thanks everybody for all your ideas, calculations and suggestions.
I have had another thought, (they come slowly now that I am over 21) and wondered if the De Waal paddle engine design could be 'tweeked' to become a three cylinder affair. The reason is really nostalgia for my youth and voyages with my Mother and Godmother on the Bristol Queen from Ilfracombe to Lundy or Clovelly. There is video of the ship here: https://www.youtube.com/watch?v=zhGUi0mG5sw. Video of her sister ship, Cardiff Queen, [https://www.youtube.com/watch?v=H42jU512n7M] also includes some stills shots of the ship at Ilfracombe with its high and rocky cliffs The first video eventually has some engine room shots and clearly shows what a lovely triple expansion engine she had. To get that feel one would need to beef up the De Waal cranks for a start...
I also recall that on some summer days when pressure was high and the air still, we could hear the beat of the paddles as the ships passed close along the coast line en route for Clovelly. Our house was at 129m above sea level and had a view west towards Lundy and north to Morte Point and the Bristol Channel. The latter was about 9km away. In those days there was little in the way of aircraft noise or traffic noise so one could hear things a long way off if the weather was right. Indeed I recall as a child lying bed on a winter night many times and hearing the trains struggling up the 1 in 36 gradient on the line from Braunton to Morthoe Station. Of course that was in the days of single glazing and bad fitting windows...
Regards
Pete
I have had another thought, (they come slowly now that I am over 21) and wondered if the De Waal paddle engine design could be 'tweeked' to become a three cylinder affair. The reason is really nostalgia for my youth and voyages with my Mother and Godmother on the Bristol Queen from Ilfracombe to Lundy or Clovelly. There is video of the ship here: https://www.youtube.com/watch?v=zhGUi0mG5sw. Video of her sister ship, Cardiff Queen, [https://www.youtube.com/watch?v=H42jU512n7M] also includes some stills shots of the ship at Ilfracombe with its high and rocky cliffs The first video eventually has some engine room shots and clearly shows what a lovely triple expansion engine she had. To get that feel one would need to beef up the De Waal cranks for a start...
I also recall that on some summer days when pressure was high and the air still, we could hear the beat of the paddles as the ships passed close along the coast line en route for Clovelly. Our house was at 129m above sea level and had a view west towards Lundy and north to Morte Point and the Bristol Channel. The latter was about 9km away. In those days there was little in the way of aircraft noise or traffic noise so one could hear things a long way off if the weather was right. Indeed I recall as a child lying bed on a winter night many times and hearing the trains struggling up the 1 in 36 gradient on the line from Braunton to Morthoe Station. Of course that was in the days of single glazing and bad fitting windows...
Regards
Pete
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Re: Antidote to Cabin Fever?
Wouldn't an easy solution to this be to use a smaller 8"-9" prop that's geared up to a higher RPM with a chain drive from the engine? This would have the added benefit of making removal of the engine far easier for transportation or maintenance.fredrosse wrote: ↑Mon Apr 06, 2020 8:11 am"Would there be enough clearance for a 12x12 prop?"
The software I have indicated the 12 x 12 prop (300mm x 300mm) at 500 RPM as approximately ideal, but the actual hull configuration is much more suited to a 9 or 10 inch (225 - 250mm) prop diameter, about 80% of the ideal diameter. No big sacrifice in efficiency with this smaller prop, maybe a few % higher RPM could be used. Difficult to go much further in details without the actual lines of the boat.
- fredrosse
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Re: Antidote to Cabin Fever?
The car top Scanoe needed step-up gearing, the engine running at 600 RPM, and the drive shaft at 1000 RPM. For anything under a few horsepower (including the 1340cc Harley Davidson Motorcycle), toothed belt drive is the way to go. It is silent and reliable, with virtually no maintenance required.
The attached picture shows the Scanoe engine, made from a 4.7 (75cc) chain saw engine. A second toothed belt drive runs the feedwater pump and oil pump, with a ratio reducing pumps' speed. Engine ran 600 RPM, pumps at about 200 RPM, the step up drive (drive shaft was near the ruler in the picture), with about 1000 RPM, then to a 1:1 right angle drive to a vertical shaft, then to the lower end of a small outboard motor lower unit, which had its own gear reduction to about 600 RPM propeller speed.
A flash boiler was used to keep weight down.
The attached picture shows the Scanoe engine, made from a 4.7 (75cc) chain saw engine. A second toothed belt drive runs the feedwater pump and oil pump, with a ratio reducing pumps' speed. Engine ran 600 RPM, pumps at about 200 RPM, the step up drive (drive shaft was near the ruler in the picture), with about 1000 RPM, then to a 1:1 right angle drive to a vertical shaft, then to the lower end of a small outboard motor lower unit, which had its own gear reduction to about 600 RPM propeller speed.
A flash boiler was used to keep weight down.
Last edited by fredrosse on Fri Apr 24, 2020 8:48 pm, edited 1 time in total.
- PeteThePen1
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Re: Antidote to Cabin Fever?
Hi Fred
What an excellent looking conversion you have done. Unfortunately, round here scrap chain saws are a bit thin on the ground so I cannot see me trying to copy you.
Pete
What an excellent looking conversion you have done. Unfortunately, round here scrap chain saws are a bit thin on the ground so I cannot see me trying to copy you.
Pete
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Re: Antidote to Cabin Fever?
Further machinations on an engine for Pete's little canoe. Locked down and looking for something different to do I remembered a little stationary engine that came my way a few years ago.
Twin, over mounted, copper boiler etc. a very nicely built model. I had never steamed it, though I did hydro it a couple of years ago and ran it on air. I dragged it out from under the bench and filled and fired it. after a bit of a struggle with the fire I did get it to run very sweetly. It will tick over at virtually nil PSI.
I thought to measure it and it has a 2" stroke with what appears to be 1 1/4" bore (guessed from the cyl cover) Running the numbers on it, it's giving a hair's breadth under 0.6Hp at 75psig (safety valve setting. I hydro-ed to 150). Very respectable from something so comparatively small, a touch under 24" long x 11" wide and 22" to flue top. The original question on here was "How heavy would suitable plant be"? The answer to that is this is 84lbs. A bit heavy for a one man job but probably doable. With similar plant this hull should still manage two medium sized adults.
Twin, over mounted, copper boiler etc. a very nicely built model. I had never steamed it, though I did hydro it a couple of years ago and ran it on air. I dragged it out from under the bench and filled and fired it. after a bit of a struggle with the fire I did get it to run very sweetly. It will tick over at virtually nil PSI.
I thought to measure it and it has a 2" stroke with what appears to be 1 1/4" bore (guessed from the cyl cover) Running the numbers on it, it's giving a hair's breadth under 0.6Hp at 75psig (safety valve setting. I hydro-ed to 150). Very respectable from something so comparatively small, a touch under 24" long x 11" wide and 22" to flue top. The original question on here was "How heavy would suitable plant be"? The answer to that is this is 84lbs. A bit heavy for a one man job but probably doable. With similar plant this hull should still manage two medium sized adults.
Retirement is about doing what floats your boat!
A BODGE : - A Bit Of Damn Good Engineering.
A BODGE : - A Bit Of Damn Good Engineering.
- PeteThePen1
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Re: Antidote to Cabin Fever?
Hi Everybody
Just a bit of a follow up to Fred's comments about the calculations he had done. Both Mike R & I now have copies of the plans so we could probably provide more data if folks are interested. Alternatively, what software are you using Fred? If it is not hugely expensive and difficult to learn I might have a go at that myself.
Regards
Pete
Just a bit of a follow up to Fred's comments about the calculations he had done. Both Mike R & I now have copies of the plans so we could probably provide more data if folks are interested. Alternatively, what software are you using Fred? If it is not hugely expensive and difficult to learn I might have a go at that myself.
Regards
Pete
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Re: Antidote to Cabin Fever?
Pete is correct we do both have a set of drawings for this craft. Unfortunately his are in PDF format for the moment, whilst mine are actually on paper. He and I have yet to bang heads on the details, but I have already spotted a couple of things to query, not the least of which is the materials list. Given time we'll get to it.
Meanwhile I have made a start on some more parts for my twin which I will report in a day or so. Well, I had to do something!
Meanwhile I have made a start on some more parts for my twin which I will report in a day or so. Well, I had to do something!
Retirement is about doing what floats your boat!
A BODGE : - A Bit Of Damn Good Engineering.
A BODGE : - A Bit Of Damn Good Engineering.
- fredrosse
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Re: Antidote to Cabin Fever?
"what software are you using Fred? If it is not hugely expensive and difficult to learn I might have a go at that myself."
The FAQ section of this forum has approximate formulas for typical launches to determine power required, engine sizing, boiler sizing, etc. Have a look at these posts to get a good Idea about launch propulsion and powering.
I also have EXCEL spreadsheets which provide better accuracy for hull analysis (as well as engine parameters), if the marine parameters are available: Admiralty coefficient, prismatic coefficient, etc. are calculated from hull dimensions, displacement, water plane area, mid section area, etc. I hesitate to share this program, as many typically misuse the spreadsheet and end up with unrealistic answers.
The FAQ section of this forum has approximate formulas for typical launches to determine power required, engine sizing, boiler sizing, etc. Have a look at these posts to get a good Idea about launch propulsion and powering.
I also have EXCEL spreadsheets which provide better accuracy for hull analysis (as well as engine parameters), if the marine parameters are available: Admiralty coefficient, prismatic coefficient, etc. are calculated from hull dimensions, displacement, water plane area, mid section area, etc. I hesitate to share this program, as many typically misuse the spreadsheet and end up with unrealistic answers.
- PeteThePen1
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Re: Antidote to Cabin Fever?
Thanks Fred.
Yes, I would agree that it is usually best to keep home brew calculators safe in house. My classic case of not doing that was to do a regression analysis of the asking prices of of steam launches by size in Funnel Magazine and offering the the outcome as an 'interesting fact'. There were huge complaints to the Committee subsequently as the price of steam launches fell due to weakened economic conditions. Oops!
Thanks to the pointer to the FAQ section. I keep forgetting that there is a lot of useful stuff there.
The paper drawings have now arrived and to my eye it is a very pretty little boat.
Regards
Pete
Yes, I would agree that it is usually best to keep home brew calculators safe in house. My classic case of not doing that was to do a regression analysis of the asking prices of of steam launches by size in Funnel Magazine and offering the the outcome as an 'interesting fact'. There were huge complaints to the Committee subsequently as the price of steam launches fell due to weakened economic conditions. Oops!
Thanks to the pointer to the FAQ section. I keep forgetting that there is a lot of useful stuff there.
The paper drawings have now arrived and to my eye it is a very pretty little boat.
Regards
Pete