Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: Lt. Raen on April 22, 2010, 03:38:36 am

Title: Prop for deep v??
Post by: Lt. Raen on April 22, 2010, 03:38:36 am
G'day I'm from Sydney Australia an am currently looking for a prop for the 1.2m deep v I'm building out of ply.

I am looking for advice on what size prop to match to the 25cc blower/vac motor i going to run in it.

also any advice on good suppliers for a prop would be welcome

Cheers, Raen
Title: Re: Prop for deep v??
Post by: HS93 (RIP) on April 22, 2010, 04:27:11 am
you may find what you need
hear



http://www.prestwich.ndirect.co.uk/

Peter
Title: Re: Prop for deep v??
Post by: w3bby on April 22, 2010, 08:34:37 am
Octura 470, 475 or 480 should be a good start I would have thought.

Check out the AMPBA site for your local suppliers http://www.ampba.asn.au/links.htm (http://www.ampba.asn.au/links.htm) and don't forget your local club for help and advice http://www.modelboatclubofnsw.com/ (http://www.modelboatclubofnsw.com/)
Title: Re: Prop for deep v??
Post by: Lt. Raen on April 22, 2010, 10:18:20 am
Thanks for all the help guys i think i have everything i need to get this baby on the water now %%
cheers, raen
Title: Re: Prop for deep v??
Post by: BJ on April 30, 2010, 08:31:16 pm

I am looking for advice on what size prop to match to the 25cc blower/vac motor i going to run in it.

also any advice on good suppliers for a prop would be welcome

Cheers, Raen

IAs a guide, it might be old (1992) but the charts are still valid. Prop Shop have however changed the description of some of their props.
See the attached Charts
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 04, 2010, 07:09:00 am
After a lot of thought on this i have decided to go with surface drive over submerged drive
I was originally going to go with a submerged drive however engine mounting really only will allow for a surface drive set up.

Anyay i want to pick your brains on what hardware set up i should go with
i was thinking the SF2 or SF3 from this site: http://www.prestwich.ndirect.co.uk/surfacedrive.htm

but i just wanna make sure on my choice before sinking anymore money into this project
 :-))
Cheers
Title: Re: Prop for deep v??
Post by: martno1fan on May 04, 2010, 07:47:54 am
You would be best getting your gear from Aus wouldnt you? theres a few good dealers over there that stock all you need.Heres one my mate in Perth uses a lot.Good prop for a weedy engine is the prather 280 or octura 480,another is the p275,basicly you need a big prop because weedys dont rev high enough to spin the smaller props fast enough so you take advantage of the torque by using a big prop.Stick a walbro wa 167 carb on it and it will improve quite a bit also,thats about the best carb for these motors but anything with similar size intake would work better than the stock carbs.
http://www.hobbydepot.com.au/
Title: Re: Prop for deep v??
Post by: HS93 (RIP) on May 04, 2010, 12:40:24 pm
You would be best getting your gear from Aus wouldnt you? theres a few good dealers over there that stock all you need.Heres one my mate in Perth uses a lot.Good prop for a weedy engine is the prather 280 or octura 480,another is the p275,basicly you need a big prop because weedys dont rev high enough to spin the smaller props fast enough so you take advantage of the torque by using a big prop.Stick a walbro wa 167 carb on it and it will improve quite a bit also,thats about the best carb for these motors but anything with similar size intake would work better than the stock carbs.
http://www.hobbydepot.com.au/

I have just spent the last month in Perth Aus and the cost of parts is 50% more than the uk I went around a few shops and met with some boaters over there (and had a great sail) and they all said the same it is cheaper to buy from the uk for a lot of stuff,in Perh there is very very little available for RC boats, plenty for helli's planes and cars
there was one excellent shop that I spoke to the manager who said there was the call for boats but they Had not been able to find a boat person to work for them, which is a shame because they where a very professional outfit
http://www.perthrc.com.au/
Peter
Title: Re: Prop for deep v??
Post by: martno1fan on May 04, 2010, 01:32:05 pm
HMM thats odd as my mate lives in Perth and has no problems with finding parts for boats ,prices arent too bad either check the link out and compair prices not much difference to be honest def not 50% difference on the items i looked at.The place ive linked is a great place for gas boat gear hes well respected and reliable.
Mart
sturt 40 aus$ or £24 versus about £20 in the uk so asaving of 4 quid but then you got shipping costs.

http://www.hobbydepot.com.au/product_info.php?cPath=37_58&products_id=147

Title: Re: Prop for deep v??
Post by: w3bby on May 04, 2010, 02:45:13 pm
...strut 40 aus$ or £24 versus about £20 in the uk so asaving of 4 quid but then you got shipping costs.
Take off the VAT from the UK price for a foreign sale. Also have to look at the whole picture, £32,90 (less vat) for the SF2, Oz price for just the strut and the flex http://www.hobbydepot.com.au/product_info.php?cPath=37_90&products_id=438 (http://www.hobbydepot.com.au/product_info.php?cPath=37_90&products_id=438) is up there, 52 Aus$ for the flex...... 92 Aus = £55............
Title: Re: Prop for deep v??
Post by: HS93 (RIP) on May 04, 2010, 02:46:35 pm
HMM thats odd as my mate lives in Perth and has no problems with finding parts for boats ,prices arent too bad either check the link out and compair prices not much difference to be honest def not 50% difference on the items i looked at.The place ive linked is a great place for gas boat gear hes well respected and reliable.
Mart
sturt 40 aus$ or £24 versus about £20 in the uk so asaving of 4 quid but then you got shipping costs.

http://www.hobbydepot.com.au/product_info.php?cPath=37_58&products_id=147



http://www.heliguy.com/Extras/Radio-Transmitters/Spektrum-DX6i/?gclid=CPaJ3u3NuKECFReX2Aodxx3xEQ

http://www.stanbridges.com.au/shop.DX6I
this was of the items I priced asPaul had just bought one a aus dollar is about 60 p , you have to rember the pound has just plumeted since xmas, no doubt the person I met over there may come on and tell you more

Peter
Title: Re: Prop for deep v??
Post by: martno1fan on May 04, 2010, 04:03:17 pm
Theres allways Hong kong thats where all that hardware comes from anyway  %).
Mart
Title: Re: Prop for deep v??
Post by: BJ on May 04, 2010, 08:42:15 pm
After a lot of thought on this i have decided to go with surface drive over submerged drive
I was originally going to go with a submerged drive however engine mounting really only will allow for a surface drive set up.

You might to take a look at http://www.modelboatmayhem.co.uk/forum/index.php?topic=23457.msg232305#msg232305 (http://www.modelboatmayhem.co.uk/forum/index.php?topic=23457.msg232305#msg232305) to go full surface drive. What you were thinking about the late Millar Agnew used to call "semi surface". There is nothing wrong with that - most of my boats are "semi" surface.
You may also want to use the attached chart to select a suitable turned exhaust length for your engine.
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 05, 2010, 04:43:30 am
Thanks for that BJ sould com in handy

Martno1fan i believe that i am using th same hull as one of your boats i cant remember which build thread i saw it but im fairly sure it was yours  :-)
Also any idea of good sites from Hong Kong matrno1fan?

The prices here in aus seem very . . . ah extravagant compared to other places around the wold also the support for boats is nearly non existant in most rc stores, seems like everyone here is interested in cars and helo's not boats.

Allt thoughts and suggestions welcome

Cheers Raen
Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 08:15:28 am
Is it the wooden deep vee your building ? if so you will love how it handles its a great hull.Go full surface drive with it thats what its designed for  :-)).Heres a good source for hardware and zenoahs if you decide later you want to get one.Johnny is reliable and fast to deliver and his gear is top notch.If you email him with your order ask for a discount if your ordering a lot of stuff he might be ok with that ok2.
Mart
http://stores.shop.ebay.co.uk/Head-of-the-River-RC-specialist__W0QQ_armrsZ1
Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 08:17:43 am
Heres another pic of my old woody is it this one your doing? how about some pics.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 05, 2010, 08:30:30 am
Yep Mart thats the one
I will take some photos when i get the chance

Cheers, Raen
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 05, 2010, 09:15:21 am
Ok so im trying to work out what i need to order here,
so heres what i have worked out so far:

Strut $19 US
http://cgi.ebay.co.uk/aluminum-strut-1-4-shaft-rc-boat-/300370504445?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item45ef7a2afd (http://cgi.ebay.co.uk/aluminum-strut-1-4-shaft-rc-boat-/300370504445?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item45ef7a2afd)
Rudder $24US
http://cgi.ebay.co.uk/aluminum-rudder-water-pickup-21-engine-rc-boat-/280430793337?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414afa5279 (http://cgi.ebay.co.uk/aluminum-rudder-water-pickup-21-engine-rc-boat-/280430793337?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414afa5279)
flex cable and tube  $25 US
http://cgi.ebay.co.uk/1-4-flex-cable-w-stub-shaft-brass-tube-teflon-lining-/280456829311?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414c87997f (http://cgi.ebay.co.uk/1-4-flex-cable-w-stub-shaft-brass-tube-teflon-lining-/280456829311?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414c87997f)
Collet $11 US
 http://cgi.ebay.co.uk/Stainless-Steel-flex-collect-1-4-cable-gas-engine-/290377518948?cmd=ViewItem&pt=Radio_Control_Parts_Accessories&hash=item439bd94f64 (http://cgi.ebay.co.uk/Stainless-Steel-flex-collect-1-4-cable-gas-engine-/290377518948?cmd=ViewItem&pt=Radio_Control_Parts_Accessories&hash=item439bd94f64)
Drive dog $8.99 US
 http://cgi.ebay.co.uk/stainless-steel-prop-nut-and-drive-dog-1-4-shaft-/280421227679?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414a685c9f (http://cgi.ebay.co.uk/stainless-steel-prop-nut-and-drive-dog-1-4-shaft-/280421227679?cmd=ViewItem&pt=Radio_Control_Vehicles&hash=item414a685c9f)
Prop $11US
http://cgi.ebay.co.uk/Aluminum-Propeller-70mm-dia-23-35cc-pitch-98mm-/290413887426?cmd=ViewItem&pt=Radio_Control_Parts_Accessories&hash=item439e043fc2 (http://cgi.ebay.co.uk/Aluminum-Propeller-70mm-dia-23-35cc-pitch-98mm-/290413887426?cmd=ViewItem&pt=Radio_Control_Parts_Accessories&hash=item439e043fc2)

For a grand total of $123.99US which works out to be Approx $137 AUD
Preswitch model boats works out at 104 pound which is approx $174 AUD
SF3, HF49 Octura X467 and collet

Is that all i need or have i missed something??

Raen

Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 10:14:21 am
You will need something to hold the tube near the engine ,either a t bar or use a plywood one,just a slot in some ply glassed between the rails works.Its just to stop the tube moving  really,silicone the tube in place at the transom to seal up the hole and fix it to the plywood at the other with  silicone .A zip tie at the motor side will stop the tube moving back till the silicone sets and its extra insurance too i suppose.Just remember its easier to take out if required if you use silicone or a t bar setup rather than glassing the tube in.What are you using for servos? you will need a high torque one for the rudder,standard is ok for throttle.Im asuming your making your own mounts for the engine? ,be sure to use rubber dampers if you are.What motor are you using?,the collet might not fit your output shaft? ,you can use a square ended flex if your using a trimmer type engine that has the square hole?.If not you will need to find a collet with the correct threads,i used a cmb .90 colett for one they have the m8 thread same as my weedy engine had.My first one had the square setup so then i had to use a ferrule to attach the cable to the shaft at the prop end using silver solder,you can also use loctite retaining compound for this.
Mart
Heres a pic of a typical ferrule setup.
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 05, 2010, 11:02:09 am
The motor is a 25cc one from a blower vac with a drive shaft ending in 5/16 UNF threaded rod. so before ordering the collet i will email the supplier and make sure he has what i need.

As for servos i havent given them a great deal of thought
am looking at this: http://www.rchobbies.com.au/store/product_info.php?cPath=506_32&products_id=50060&osCsid=f850bba4a24216cd9a900aa0b3e7a826 for a radio and was going to choose a servo once i had the prop shaft/ engine mounting sied of things better organised
a high torque servo like this? such as http://www.rchobbies.com.au/store/product_info.php?cPath=506_60&products_id=14717&osCsid=f850bba4a24216cd9a900aa0b3e7a826
electrics might take a while as once i have the surface drive hardware i have to do some glassing as well as save some more money for the radio gear. :embarrassed:

with the flex cable that i listed do i need a ferrule as it appears to end in a stretch of unthreaded bar for the prop, or is the ferrule meant to ensure it doesnt stretch the cable pulling the prop away from the strut?

The T-bar you talk of i should be able to make out of spare ply or aluminium.

will take some photos 2moro after uni to make things clearer

Raen

Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 11:12:37 am
The ferule is only needed to atach the flex to a  stub shaft if your using the square end at the engine.If using the collet at engine you can just buy a standard round flex setup.As for radios if you want 2.4 then id go with the futaba fasst system that hops from channel to channel not just between two.The latter dont like water and can be a problem especially in fast gas boats,so if you want 2.4 go with the futaba fasst  :-)).I use the old 6ex futabba fasst system that was designed for helis and planes and its great,you can pick those up second hand or theres a newer model out now.For servos go for one with metal gears if you can for the rudder.
Mart
Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 11:16:13 am
This is the radio i use on all my boats,looks like it needs a reciever,maybe he has those too .
Mart
http://cgi.ebay.com.au/Brand-New-Futaba-6EX-2-4ghz-Fasst-RC-Airplane-Radio-/270571218159?cmd=ViewItem&pt=Radio_Control_Parts_Accessories&hash=item3eff4d24ef
Title: Re: Prop for deep v??
Post by: martno1fan on May 05, 2010, 11:25:23 am
Just a bit of info on the flex cables,what happens is under load they shrink a bit so you need to leave a gap of arround 1/8-1/4" between drive dog and strut hub.If using the square setup with ferrule this wont matter as the cable floats inside the square hole at the engine end.As your using the collet setup that holds the flex firm you will need the gap between dog and strut to allow the cable to shrink a bit without binding on the strut.Look forward to the pics of your boat  :-)).
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 06, 2010, 06:44:47 am
Ok finally got some shots of the boat. its not particularly pretty at the moment, but its the first time i have built anything like this so im quite happy with the progress so far.
At the moment m biggest prblem is that the 2 pieces of ply for the hull didnt meet at the keel so i am going to glass a keel in which shouldnt be too much hassle, however, i want to work out the running gear before i do this part.
Comments welcome  :}

(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Boat1sideresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Boat1Bowresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Boat1Sternresized.jpg)
Title: Re: Prop for deep v??
Post by: martno1fan on May 06, 2010, 09:18:57 am
Not sure why the ply didnt meet at the keel,usually you glue it up starting at the transom and work forward,are you sure you had the two pieces the right way round ?.The problem i see looking at yours is the motor is high maybe rasing the sides at the rear would have been a good idea,thats what i did on mine.I raised the sides up at the rear to the same height as the highest part of them.Im sure you will be ok but when slowing down you may get backwash swamping the boat so dont slow down suddenly lol.Did you use rubber dampers on the motor mounts?.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 06, 2010, 09:30:19 am
The engine is just sitting in there at the moment (not attatched to the bulkheads or anything)
rubber mounts will be mounted and the motor lowered when i have worked out where the prop shaft will allow the engine to sit
I am not entirely sure why it didnt meet up, however it should be fine
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 10, 2010, 01:25:58 pm
As for radios if you want 2.4 then id go with the futaba fasst system that hops from channel to channel not just between two.

Mart this seems to suggest that there asre more options than just 2.4ghz for a radio, what are the other options as i thought that 2.4 ghz was the only viable option????

Sorry for all the questions {:-{

Raen
Title: Re: Prop for deep v??
Post by: BJ on May 10, 2010, 02:24:40 pm
Mart this seems to suggest that there asre more options than just 2.4ghz for a radio, what are the other options as i thought that 2.4 ghz was the only viable option????

Sorry for all the questions {:-{

Raen

See http://www.rc-airplane-world.com/rc-frequencies-australia.html (http://www.rc-airplane-world.com/rc-frequencies-australia.html)
You have   
    * 29MHz FM primarily surface vehicles
    * 36MHz FM primarily aircraft
    * 40MHz FM also for general use

You need to read the article carefully
Title: Re: Prop for deep v??
Post by: martno1fan on May 10, 2010, 04:40:02 pm
Not sure what frequencies are legal over there but cheapest safe radio to use would be an FM set,dont use am radios with spark ignition engines though.Also be sure you use a resistor plug on the engine,plug should have the letter r on it.Fm radios are what everyone used to use before 2.4 ghz came out and they work just fine,many still use them.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 12, 2010, 06:22:30 am
Ok whilst i am waiting on some parts i decided to have a think about how i could layout the running gear in the boat.
So far this is what i have got:
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Surfacedrivelayup_resized.jpg)

The main part im not sure about is the actul prop shaft tube and whether it should be mounted like shown or on more of an angle to reduce the flex after the tube

Any help greatly appreciated

Raen
Title: Re: Prop for deep v??
Post by: martno1fan on May 12, 2010, 07:57:47 am
Hi you will need to have the tube go much further towards the motor,withing 1-2" i usually dont have more than 1 1/2" if i can help it.This means you have to bend the tube to meet up at the motor,the angle you have and the bend your showing is perfect.To bend the tube install the flex into it and slowly bend it over your knee till it fits pefectly,then cut it to its final length leaving no more than 2"gap max,any more and the cable can whip and snap.Heres a few pics of one of my hulls i did for a customer last year it shows the angle of the motor and the bend of the tube and the length needed etc.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 12, 2010, 08:11:16 am
Ahh ok thanks for clearing that up Mart, suspected that would be the case but couldnt remember seeing a clear photo or diagram of this and wasnt too sure about the bend distorting the tube. But i guess by bending the tube with the flex inside and keeping the bends shallow it stops the tube distorting too much.

Anyway just waiting on my first ever eBay purchase, just hope it all comes as promised lol  :D
Title: Re: Prop for deep v??
Post by: martno1fan on May 12, 2010, 02:00:45 pm
Another way to bend tubes is tape up one end and fill with sand or salt then tip a bit out say 1" and tape up the other end and bend slowly ,this stops it kinking or colapsing,ive never kinked a tube yet by using either method  ok2.Just be sure to use 5/16 internal  diam tube ,thin walled brass is what you want.k&s tubing works if you can get it long enough but either way its the thin walled stuff you want.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 25, 2010, 12:55:34 pm
Whilst i have been waiting for some parts to arrive (should be here tomorrow  %%) i have been doing some research into radio gear,
I initially settled on a Futaba 6ex tx with R617FS Rx and a standard and high torque servo.
I just want to confirm that this would be a good choice before i sink money into it.
Or would a pistol grip style be better for this kind of boat or is pistol over joystick (is that the right term???) just a personal preference thing
(must admit i do prefer the joysticks though)

Sorry bout all the questions but i don't want to get this wrong   :-)

Thanks

Tim
Title: Re: Prop for deep v??
Post by: Bill D203 on May 25, 2010, 04:34:13 pm
Just my choice is the Futaba 2.4 Ghz stuff. I run off shore boats and have not had one prob since i got it. I found the sparky engine upset 40mhz radio and had loads of trouble which all changed when i went 2.4ghz.
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 26, 2010, 06:16:29 am
Got home from uni to find these waiting for me  %%
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/StrutandRudderresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/PropandDognut-propnutresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Partsresized.jpg)
The prop appears to ba an octura x470 which is surprising as it wasnt listed as a brand name product (maybe just a rip off i dunno)
All the gear appears to be of a high quality with only a few minor issues appearing, these are:
The prop nut has no grub nut (not a huge deal to me at the moment as the prop and dog nuts werent even listed as coming with the flex shaft  ok2)
The rudder is attatched to the 90 degree mounting bracket by two short screws but no locking nut which i might change as i would feel a little more comfortable if it had a lock nut n it (dont want the rudder falling off on me  %) )
Only the flex collet to arrive before i start to put it in the boat.
However still a lot of work to do to the hull between now and then,
I have to add a chime line and was thinking of using atuobody filler to build up a line then cover with epoxy resin when i resin the rest of the hull would this be a good way to make a chime line?

Cheers, Tim
(p.s. perhaps this thread might need a more appropriate name now that it has well and truly move on from just a prop choice  :-))
Title: Re: Prop for deep v??
Post by: w3bby on May 26, 2010, 09:48:51 am
Choice of stick or pistol radio is just personal preference. Most of the FSR-V guys I know use a stick whilst most of the offshore and hydro guys use a pistol, mainly down to the fact that the V boats need more channels. Choose that which you are most comfortable with. Personally use a Futaba 3PM 2,4GHz Fasst. One good thing is that it has an inbuilt failsafe, has to be set every time if you are using analogue servos but can be a real boat and lifesaver.

Hardware looks fine although the bullet propnuts aren't my favourite, I prefer a locknut. The bottom screw holding the rudder blade I would replace with a brass or nylon sheer bolt so the rudder will kick up without destroying the transom if you hit debris in the water.
Title: Re: Prop for deep v??
Post by: Lt. Raen on May 28, 2010, 07:20:17 am
Got some work done fibreglassing the hull this morning
And started work on making up some chimes for it as well

(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Chimesresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Chimes2resized.jpg)

During the week i made an engine mount as well
The engine is spaced by rubber mounts at all points its connected to the mount and there will also be rubber between the mount and the hull to help reduce the effects from any vibrations
And dont worry that exhaust is getting replaced  :-))
Just looking at ways of making a pipe for it

(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Motormountresized.jpg)

Still need to add more resin to the hull before i can achieve a smooth finish but i think i will add the chimes before working on getting the hull smooth

I will need a name and colour scheme before long  %)
im thinking black with red trim, no idea about a name yet though

Any help and comments appreciated

@w3bby good point about the bolt on the rudder went and got a brass bolt today to try to minimize damage in the event of a strike on the rudder. Yeah i think i prefer the sticks just never really enjoyed my mates pistol style radio, the 6ex also has an inbuilt failsafe and i found one at a good price so i will most likely get that

Cheers, Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 01, 2010, 11:27:57 pm
6 ex is a good radio does your rx have the two small antennas or one?,mine has two and i even ran mine inside the radio box with no issues.Personally id have filled the keel and kept the glass for inside as it would save a lot of work sanding ,be sure to wear a mask when you do.You might want a slightly bigger prop something like a 275 or even a 280 prop or failing that go for a 3 blade with 70 or so mm diam.Are you going to add strakes under the bottom of the hull?,they really help create lift especially when your using a weedy engine that doesnt have much power.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 02, 2010, 04:44:17 am
Strakes?? what do u mean by this

I was talking to a friend who makes full size boats and he recommended adding a fin to the keel to help with turning

The keel is quite smooth at the moment, between the resin and the filler i have applied since these photos its turning out quite nicely.
although your right it has required a lot of sanding with the wet and dry (wet) to get to this stage.
A facemask is a very good idea, i have been wearing a facemask whenever i sand

I will be getting the 6ex with the 2 small antenna

I will be ordering one maybe 2 more props once funds allow so i will remember to up size  :}

Thanks for your help

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 02, 2010, 07:58:01 am
Hi Tim i cant find pics of my old woodys bottom,must be some on my old thread?,anyway if you look on most fast vees they have strakes on the bottom to add lift.Most stop before the transom but on these woodys with a trimmer motor id advise running one  either side of the keel about half way between keel and chines and go from transom to arround half way or at least a third of the length of the hull they will help get the boat up on plane easier especially with a low power motor.
Mart
Heres a pic of one of my Apache Hulls showing strakes,these dont go to the transom but on yours i would but id just use one either side .
Title: Re: Prop for deep v??
Post by: martno1fan on June 02, 2010, 08:22:12 am
Managed to get some off my orriginal build thread on another site lol.I used pins to hold it while the epoxy set but you can pin it permenantly at the transom if your transom is thick enough  ok2.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 02, 2010, 08:27:44 am
Ahhh right thats making sense, just like on the full size things lol

hmmm i will have to work on that one, i dont think i will be able to use quite the same method as i did for the chimes but im sure something will present itself when i have a poke around bunnings  ;D

Tim
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 02, 2010, 09:14:00 am
Just been having a think about the prop size
In full size ski boats if you increase the pitch of a prop on a given engine then you change the "punch out of the hole" and the top speed.
The punch out of the hole i refer to is i guess the take off of the boat from a standing start. this usually gets better with a smaller pitch then a large pitched propeller until some point where it becomes counter productive.
This reduction in pitch however tends to create a lower topend speed, actually a lower speed across the whole rev range
That is to say that:

at 2000 rpm with a 21" prop the boat may be going 35 mph
but with a 19" prop pitch the boat will only be going 30mph at the same rpm but the 21" may tend to "bog down"

So you have to have a tradeoff between punch out of the hole (torque?????) and top end speed
Does the same thing occur on the much smaller scale of the RC boats?
For example the 98mm pitch prop i have at the moment might give more punch our of the hole but less top speed so if i retain the same diameter of 70 mm or there abouts and just increase the pitch i would get a faster boat assuming that its the same as my personal experience with full sized boats.

I guess i can only really confirm or deny this theory by actually testing different sized props but I'm interested to know your views on pitch

also Whit effect does increasing prop diameter have?

Thanks once again  :-)

Tim (feeling like i should stop asking so many questions  :embarrassed: )
Title: Re: Prop for deep v??
Post by: martno1fan on June 02, 2010, 12:34:07 pm
Your thinking along the right lines,reason im saying go with the prather 275 or the 280 is been larger and having more blade you can take better advantage of what weedy motors have which is reasonable torque,the 270 prop will need to spin much faster to get the same results which isnt possible with a weedy engine they just dont have the rpm so most go with the larger diam props.the two i mentioned ar probably about the best for most stock weedy engines.Save the smalelr diam ones for when you decide to geta  zenoah or similar  :-)).Be sure to ballance and sharpen the prop if you get a brass or stanless one,the ali ones dont usually need it.
Mart
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 03, 2010, 08:27:53 am
Just been working on making the hull smooth in preparation for its final coat of resin, so much sanding here   :((

Martin i was just wondering how you secured the deck to the hull? i have been looking at mine and have thought of using some
aluminium brackets but was just wondering if you had a more "elegant" solution.
Also where did you put the fuel tank? i am getting another one from the one that originally came with the motor as it didn't fit
due to its strange shape. I wasthinking of mounting it in front of the motor (towards the bow slightly) I guess i want to keep
the weight as far back as possibly at this stage.
Your comments about prop sizes makes sense, If i do end up getting a stainless or brass prop how do i sharpen/balance them?

With the strakes should i bring them up to the point where i have put my chimes?

Well I'm going to get back to sanding thanks for all your help

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 03, 2010, 10:02:28 am
Hi to join the deck what i did was added some spruce strips to the top edge of the sides and glue the top on taping it down as i went and left it till it set.The tank usually goes in front of the motor but try and get the hull ballanced with everything in the hull roughly where its going to be mounted that means hang the hardware on the back too sit the hull on a dowel and move things arround till she balances on it.Go for a balance point of arround 30-32% measured from the transom.Do this before mounting the motor and use the motor as your way to find the balance point,i sometimes half fill the tank with fuel that way as you use fuel you know the balance wont change too much.You can make the strakes the same as your chines in length but even 2/3rds would be enough.For sharpening and balancing checkout the vids in the link and be sure to wear a  mask,you will need a prop balancer too or save some work and buy a balanced prop.
Mart
http://www.youtube.com/watch?v=fVLdD9xAm0Q
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 04, 2010, 11:25:16 am
With the weather here in sydney so attrocious of late i have been looking into a new carby to help with performance.
I have been looking for the wa-167 but it seems to be very hard (if not impossible in aus) to come by.
I was wondering if the wt-644 or wt-257 could be used and what is the advantages/disadvantages of each?

Thanks, Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 04, 2010, 12:11:37 pm
Hi i think both of those would be too big a bore for your motor,the 167 is an 11 mm diam bore i think where as the others are 13 mm if memory serves.If you had to use either of those id go with the 644 with the choke,but if you go to any lawn mower shop you may find a carb with a 11 mm diam bore.Whats the bore on yours now about 8-9mm ?.
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 04, 2010, 12:24:29 pm
hmm yeah the specs say 12.7mm bore for the 257 and 644, i was thinking the 644 with the choke would be better (its also cheaper lol)
So an 11mm bore hmm
as for the one on there now i will check tomorrow, i know that the one on there has troubles idling
am hoping a pipe on the exhaust will help to reduce this issue

well i may as well start looking an 11mm bore carby thenTim, waiting for his workspace to dry out  :D
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 04, 2010, 12:32:29 pm
Well i had to go outside anyway so i had a quick look and if im looking at the right thing it appears to be about 9mm in diameter

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 04, 2010, 04:20:51 pm
Try one from a chainsaw some of those seem to be a bit larger,failing that try the 644 just not sure how well it will work lol.
Title: It floats!!!
Post by: Lt. Raen on June 09, 2010, 09:24:58 am
Finished adding the resin to the hull and took it to a local creek for some "sea trials" lol
Well all went well and I'm glad to say she floats  {-)
With the motor in and some rocks to simulate radio gear and fuel it seems to be sitting quite nicely in the water,
my mate thought it was possibly a little low at the bow but i think it was sitting nicely considering the lack of rise in the hull. (unfortunately no pics of the water trials)

Been searching around for carbs second hand at local mower shops so far no luck but its not urgent so I'm not worried.

Been looking at the exhaust of late and am going to make up a pipe out of aluminium,
will be using an oxy torch to weld as its the only form of welding i am any good at at all lol

Radio an servos turned up in the last two days (Futaba 6ex, r617FS rx and 2 S3003's still need a high torque but that will come lol)

Anyway on to the pics

(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Fibreglassedresized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Fibreglassed4resized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Fibreglassed3resized.jpg)
(http://i682.photobucket.com/albums/vv189/Raen_09/25cc%20Boat/Fibreglassed2resized.jpg)

Still not 100% happy with the Hull could be smoother but i think it will stay as is for now whilst i work on the deck
only a fuel tank and batteries for rx to go and i will have everything i need to test her out

I still need a colour scheme and name so any suggestions are welcome

Cheers, Tim
Title: Servo cables
Post by: Lt. Raen on June 09, 2010, 10:57:03 am
One more thing,
looking at the Rx and the servos im a bit confused as to which way to plug the servos in
im assuming that as there are three wires (+ve -ve and signal )
the red is in the middle but do i install the servo so the black wire is closest to the outer edge of the servo case or to the centre of the servo??
This in turn willl tell me how to plug the battery/switch harness in i suppose

heers, tim
Title: Re: Prop for deep v??
Post by: DickyD on June 09, 2010, 12:13:45 pm
Usually, -ve goes to the edge of the receiver and signal towards the centre of the reciever.
Title: Re: Prop for deep v??
Post by: martno1fan on June 09, 2010, 01:45:34 pm
Shes coming along niceley mate keep up the good work,as regards pipe if you want you can just keep the can on you wont gain anything from a  pipe with these motors unless you plan on modding it slightly.Some people block the exit hole on the can and drill a larger one or install another exit pipe if you understand me it gives you a slight gain in power.If you really want a tuned pipe you can make a flange to fit the engine and tap it for the header pipes we use on the zens thats how i did it.If you do it you wanna buy either a 90% header with water cooled flange or a 105% header with flange that one will bring pipe out over the centre of the transom.You will then need to water cool the header flange and pipe  either by using a rudder with a water pickup or hang a pickup on the transom,you can make them using brass tube cut at an angle.I used a welded up wrap to centre pipe but i had to cut it and extend the bend to make it fit,i used an old piece of header to sleeve it and extend and silver soldered it together,if i did it again id use a seperate header and pipe but its all i had at the time.
Mart
Title: Re: Servo cables
Post by: w3bby on June 09, 2010, 02:22:39 pm
One more thing,
looking at the Rx and the servos im a bit confused as to which way to plug the servos in

Futaba plugs have a small tab that sticks out, the receiver has indents, they will only go together one way. http://www.fatlion.com/sailplanes/servos.html (http://www.fatlion.com/sailplanes/servos.html)
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 10, 2010, 08:31:59 am
Thanks for the comments guys.

@DickyD & W3bby had another look and there is a notch which puts the -ve on the outside (although it can go both ways without any hassle lol)

@martno1fan The pipe will be a wrok in progress as i want to finish the boat and have it runing with the stock exhaust on before i really start to think about making a pipe which would prob include an expansion chamber

hopefully i can install all the electrics 2moro and find some foam to ho under the deck which i made a start on today

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 10, 2010, 01:42:34 pm
Poole noodles mate  :-))
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 10, 2010, 02:08:30 pm
Haha
yeah I have been keeping an eye out for pool noodles, not too many about at the moment
winter and all that, been pretty cold here (to me anyway  ;D )
I know some people with pools so I might see if they have any old ones that are no longer being used
won't matter if they are a bit tatty anyway

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 26, 2010, 08:39:35 am
Is it wet yet ok2
Title: Re: Prop for deep v??
Post by: Lt. Raen on June 26, 2010, 09:53:06 am
HAHA
Not yet there hasn't been any progress of late because of uni exams.  >>:-(
But i finished my last exam today so i will be getting back into the swing of things tomorrow

Tim
Title: Re: Prop for deep v??
Post by: martno1fan on June 26, 2010, 03:30:11 pm
Ok mate good luck with it and your exams   :-))
Title: Re: Prop for deep v??
Post by: Lt. Raen on July 01, 2010, 08:44:00 am
OK just an update for anyone who is interested, i have been working on the RC side of things this week and have just today started to install the steering servo. the arm i have from the servo horn is a touch too short so i will have to make some modifications to the arm to make it longer (by about 1 or 2 cm)
Still trying to work out a way to affix the throttle servo.

One thing i have noticed is that when i have had the RC gear all wired up and turned on, the throttle servo (on channel 3) will suddenly shift to dead reverse after a couple of minutes of no user input on channel three. I dont know why this is happening any suggestions greatly appreciated.

(photos soon i promise  :})
Tim