Recently completed, this DUMAS kit is a bit of a disappointment in that its stability - or lack of it - looks quite frightening sometimes. it can take on an alarming list even in a straight line although it takes up a quite satisfactory 'lean into the corner ' when making a turn. Adding and moving weight around has yet to solve this awkward looking performance and I have yet to buy two batteries so the battery weight can be moved lower and possible more to the rear. Speed is not a problem but there is no way that anything like full throttle can be attempted. There is little freeboard and a list looks very alarming at speed! Any ideas? (Motor: Turnigy Aquastar 3660-1460kV) (ESC: Birdie) (4/10)
Well , the hull strakes may be a tad too thin and adding another outer strip to the strips may help . And as I cannot see the bow do the strakes ( I should have called them spray rails ) run ALL the way up to the bow as in the full size . Just at the varying side hull factor to the bottom skin hull factor at the strakes they actually lift the hull as speed increases, we are operating on a planing hull design. I built my Aerokits Large Crash Boat 30/40 odd years ago and had this problem also it was much Toooooo heavy ( for me in those days ) and increased the kit spray rails form 1/8 square to vary 1/4 to 3/16 full length with a bit of the bottom angle of the strake at a shallow "V " to the bottom hull skin and on my sea queen and the old Veron Fast Patrol boat and the ( 48 inch ) scratch British Power Boat co Seaplane tender and the old Black Marauder Torpedo boat. All with worn out Donks , but all capable of Planing at scale ride. As newer motors from better funds came about I needed less revs for a nice ride . All hulls tended FLATTER in turns as well. Just that self engineered bit worked for me despite a fair bit of work to add the spray rails. I had to be careful to NOT spoil scale appearances. Also on my Range Safety Launch, same treatment. It rises as well as the full Size. I have to run my very OLD Models in the Salt Water Lake Channel with a lot of chop in Lake Illawarra in OZ, (what does a Mill Pond Look like?). Maybe the wave energy has a slight mechanical effect ? Anyway it works . Just some help Regards to all from the colony LYLE. PS ALL my Boats are I/C which has the grunt and revs in my "heavy" models. I am not clever with electrics, at all.
Hi Lauriem,
Ran over your post somewhat late 🤔 cos I ain't bin on the site that long.
Ref your 'alarming list' problem.
Did you build your 109 à la Dumas with a single screw or scale true with three?
If with a single screw that would explain your list!
The torque reaction of a single screw and it's action on the hull would cause that.
It's caused by the water pushed up from the single prop acting on one side of the hull only.
Fitting at least two shafts rotating in opposite directions would cure that.
I'm puzzled why no one else picked up on this over the last six years! 🤔
You've made an excellent job of you 109 'as built'👍
I intend to restore mine in Pacific green camouflage as used in action.
Cheers, Doug 😎
BTW I have a PT109 on the stocks being restored.
Came to me with 2 shafts. I intend to refit it with three.
Port and starboard brushless rotating inward, centre brushed for low speed manoeuvring, rotating clockwise. Rotation directions as seen from behind the vessel.
Dumas description specifies a single shaft!☹️ and NiCads!!?? 🤔😝
"Description
The one and only PT-109 has been a standard of the Dumas line for well over 40 years. Over those years there have been many improvements on the original model and there has even been revisions on the revisions till we have gotten to where we are now. The current version uses a variety of material to simplify and improve overall construction. Some of the quality features include:
*Die-cut poplar plywood frame
*Die-cut birch plywood cabins
*Die-cut PVC external sheeting
*Cast metal deck fittings
*Full-color decals
*Step-by-step Instructions
*Full-size drawings
Over 40 years and still going strong, The One and Only PT-109
Length: 33″
Beam: 9″
Scale: Approx. 1/30
Additional parts required for R/C
#2362 Running Hardware Kit (single screw)
#2025 6v 10,000 RPM Motor
#8314 Electronic Speed Control
#8302 7.2v Nicad Battery Pack
#8315 NiCad Battery Charger
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Ran over your post somewhat late 🤔 cos I ain't bin on the site that long.
Ref your 'alarming list' problem.
Did you build your 109 à la Dumas with a single screw or scale true with three?
If with a single screw that would explain your list!
The torque reaction of a single screw and it's action on the hull would cause that.
It's caused by the water pushed up from the single prop acting on one side of the hull only.
Fitting at least two shafts rotating in opposite directions would cure that.
I'm puzzled why no one else picked up on this over the last six years! 🤔
You've made an excellent job of you 109 'as built'👍
I intend to restore mine in Pacific green camouflage as used in action.
Cheers, Doug 😎
BTW I have a PT109 on the stocks being restored.
Came to me with 2 shafts. I intend to refit it with three.
Port and starboard brushless rotating inward, centre brushed for low speed manoeuvring, rotating clockwise. Rotation directions as seen from behind the vessel.
Dumas description specifies a single shaft!☹️ and NiCads!!?? 🤔😝
"Description
The one and only PT-109 has been a standard of the Dumas line for well over 40 years. Over those years there have been many improvements on the original model and there has even been revisions on the revisions till we have gotten to where we are now. The current version uses a variety of material to simplify and improve overall construction. Some of the quality features include:
*Die-cut poplar plywood frame
*Die-cut birch plywood cabins
*Die-cut PVC external sheeting
*Cast metal deck fittings
*Full-color decals
*Step-by-step Instructions
*Full-size drawings
Over 40 years and still going strong, The One and Only PT-109
Length: 33″
Beam: 9″
Scale: Approx. 1/30
Additional parts required for R/C
#2362 Running Hardware Kit (single screw)
#2025 6v 10,000 RPM Motor
#8314 Electronic Speed Control
#8302 7.2v Nicad Battery Pack
#8315 NiCad Battery Charger
#8812-1 Two Channel Radio with one servo"
https://www.dumasproducts.com/product/pt-109-kit-1233/