Model Boat Mayhem - Forum

Dry Dock / Shipyard: Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: triumphjon on April 15, 2010, 10:46:40 PM

Title: surface drives / rudders
Post by: triumphjon on April 15, 2010, 10:46:40 PM
haveing given up on the intercepter ( seive ) im makeing my own replacement , can anyboby advise me the best measurements to the shaft & rudder positions from the transome please ? as i normally stick to submerged drive boats ! 
Title: Re: surface drives / rudders
Post by: andyn on April 15, 2010, 11:58:19 PM
Can we get some pictures and dimensions of the boat?
Title: Re: surface drives / rudders
Post by: triumphjon on April 22, 2010, 04:13:04 PM
mono hulled , moderate vee ,although fairly shallow at the transome , its  600 mm long and a beam of 200 mm  constructed of 3mm keel and bulkheads , skinned with 1.5 mm birch ply , im sorry no photos yet as its still upside down on my biulding board !  sorry for the delay in replying ive had to replace the computer screen !
Title: Re: surface drives / rudders
Post by: andyn on April 22, 2010, 06:18:10 PM
Ok then, you want it so that the centre of gravity is about a third of the total length forward from the transom. If you get a surface drive setup (Dave Marles sells them, Prestwich Model Boats), resin / glass it in then chuck all your kit inside the boat where it should roughly sit you can place things to suit from there.

For surface drive, you need the shaft to exit the boat as close to the bottom of the transom as possible. The flexi shaft can be cut with a hacksaw (slowly and carefully) then tidied up with a file so don't worry about the measurement of shaft and tube too much.
Title: Re: surface drives / rudders
Post by: triumphjon on April 22, 2010, 09:35:16 PM
i was hoping to use the old solid shaft from the last hull , fitted at the lowest point in the transome , at as close to horizontal as possible , id like to know what is the best length to mount it from the stern ? im not looking to use it to race with on a competition level .
Title: Re: surface drives / rudders
Post by: andyn on April 22, 2010, 10:10:53 PM
I've tried solid shafts as surface drive, trust me, it doesn't work...
Title: Re: surface drives / rudders
Post by: Bill D203 on April 23, 2010, 05:57:38 PM
I've tried solid shafts as surface drive, trust me, it doesn't work...
They don't bend very well do they Andy {-) {-) {-)
1/4" fleix drive as sold by PMB will do the job and will last for sometime.
Title: Re: surface drives / rudders
Post by: andyn on April 23, 2010, 06:28:50 PM
http://www.astecmodels.co.uk/catalog/product_info.php?cPath=1_79&products_id=179

This should see you well.
Title: Re: surface drives / rudders
Post by: triumphjon on April 23, 2010, 08:27:40 PM
i dont see why a short solid shaft exiting as low as possible in the transome shouldnt work , after all its thte rudder that we use to steer with ? unfortunatly as im a carer for my partner my boating is done on a very limeted budget ! .  <:(
Title: Re: surface drives / rudders
Post by: andyn on April 23, 2010, 08:37:06 PM
All that happens when you try that is that the motor will rev its nuts off, make a lot of disturbance under the water and you'll get no forward motion whatsoever. The only way it's ever work is if you could get the shaft to exit at 90 degrees to the transom and that isn't going to happen...
Title: Re: surface drives / rudders
Post by: triumphjon on April 23, 2010, 09:08:00 PM
i really cant see a problem in useing a solid shaft , as my origanal request was could anybody advise to the distance from the transome to the prop ?  surely you can understand the power loss by useing a flexible cable to transmit rotation to a prop ?  unlike some modellers ive not got deep pockets !
Title: Re: surface drives / rudders
Post by: andyn on April 23, 2010, 10:31:05 PM
Trust me, a solid shaft won't work on surface drive. Been there, done that, given up on the model.

There is actually less power loss in a well greased / oiled flexi system than a straight drive.
Title: Re: surface drives / rudders
Post by: triumphjon on April 24, 2010, 02:55:26 PM
why are you so against a soild shaft , its worked for decades in full size craft .  rather than answer my origanal request for the distance from the stern the prop needs to be to draw its own water some people like to spend needless money on making a propshaft run around corners !
Title: Re: surface drives / rudders
Post by: w3bby on April 24, 2010, 04:22:35 PM
....... can anybody advise me the best measurements to the shaft & rudder positions from the transom please ? as i normally stick to submerged drive boats ! 
As you normally stick to submerged drive boats why reject the advice of someone that normally drives surface drive boats?
Andyn states he has tried it and given up, I have never tried a solid shaft surface drive so can't give you first hand experience but let's be honest if it was the best solution we would all be using it.
The only person I can recall using solid shaft on a surface drive was from the USA and had one running on his outrigger hydro.
Full size craft may not use flex drives but they do use UJ's and CVJ's to achieve the correct drive angle at the stern, something not possible with a solid shaft.
Title: Re: surface drives / rudders
Post by: triumphjon on April 24, 2010, 06:50:26 PM
its the content of "advice "   full size craft do use uj s & cv joints , which is exactly the same as we do on a smaller scale ! if you read the content   of advice its pure spend pots of money
Title: Re: surface drives / rudders
Post by: grasshopper on April 24, 2010, 07:29:24 PM
compromise is possible chaps!

Solid shaft - at correct angle, inline with hull bottom - whatever distance is recommended from transom connected to motor via:

https://shop.graupner.de/webuerp/servlet/AI?ARTN=3345.L

should work shouldn't it?  better if the inboard end of the shaft and tube was ball raced though - and not overly expensive.
Title: Re: surface drives / rudders
Post by: Martin [Admin] on April 25, 2010, 07:57:39 AM

A couple of options;

1. Piano wire drive. You'll need a couple of solid couplings at each end but piano wire was the drive of choice before flexy wire drive.
2. I've used both Graupner and Robbe UL's on my boats with no real issues.

My Graupner 'Arrow' eventually had an Irvine .25 (4cc) glow motor with solid shafts and plastic UJ's and that worked
 well, without too many issues. The coupling did fail once... when i ran the boat up the bank at full chat!  
  http://www.modelboatmayhem.co.uk/My_models/06_arrow.htm (http://www.modelboatmayhem.co.uk/My_models/06_arrow.htm)

The tiny Graupner 'Cobra' had an Areo converted 2cc motor that screamed it's little guts out trearing across the lake. Again a setup
 with olid shafts, plastic UJ's & strudder.

The Robbe electric 'Little Devil' comes also utilises a 'Strudder' with solid shafts and UJ's, the Robbe 'Scarab' comes with two!

My Hydrofoil used a home fabricated piano wire drive using nothing more than an battery drill.....
Title: Re: surface drives / rudders
Post by: triumphjon on April 25, 2010, 10:47:56 PM
finally some sensible modellers who can understand we dont all have lots of disposeable income !  soilid shafts  a couple of uj s  and a strudder unit is the way i wanted to try ,  just need to get a strudder unit ! 
Title: Re: surface drives / rudders
Post by: andyn on April 25, 2010, 11:08:01 PM
And you reckon outdrives are cheap do you? They're awful too...

I give up...

(http://brainshavings.com/images/facepalm.jpg)
Title: Re: surface drives / rudders
Post by: john54 on April 26, 2010, 03:54:04 PM
I Dont want to "Rock the boat" so to speak {:-{ When i was in to fast leccys (On A Budget {:-{) I used solid shafts a lot  ok2 On a 20in - 25in Deepvee hull about 5in of shaft from transome to prop @ as finer angle as poss . It worked very well on my Dateline & Zoom 2 hulls useing  700bb on 14cells  &  3000kv brushless on lipo 4s :o knocking on for 40m.p.h  ok2 With no worrys @ all . I must of got lucky then ?
Title: Re: surface drives / rudders
Post by: john54 on April 26, 2010, 03:59:37 PM
As for the rudder i used this one.

http://cgi.ebay.co.uk/RUDDER-WEDGE-SMALL-model-boat-nitro-100mm-long-electric_W0QQitemZ120560925860QQcmdZViewItemQQptZUK_ToysGames_RadioControlled_JN?hash=item1c11fdbca4
Title: Re: surface drives / rudders
Post by: Martin [Admin] on April 26, 2010, 04:06:00 PM
Don't bother John, Andy's too young to listen to us dinosaurs!   ok2
 He doesn't believe that we could build boats out of scrap, wood, and things not bought from a website!  
Title: Re: surface drives / rudders
Post by: john54 on April 26, 2010, 04:14:40 PM
Fair Play Mate :-)) No More pearls of wisdom from an old f*rt then? {:-{Whos been there & done it  (And made mistakes :embarrassed:)
Title: Re: surface drives / rudders
Post by: Bill D203 on April 26, 2010, 04:20:27 PM
Don't bother John, Andy's too young to listen to us dinosaurs!   ok2
 He doesn't believe that we could build boats out of scrap, wood, and things not bought from a website!  
Nicely put Martin.
If it works then do it. Why not? They all said 2.4ghz radio would not work in a offshore boats as there is to much spray ect. WELL it dose and it dose it well.
So go with the flow.
Happy boating :-))
Title: Re: surface drives / rudders
Post by: john54 on April 26, 2010, 04:28:56 PM
Been useing 2.4 radio  in fast leccys for the last 3yrs  ok2 Fair lot of sprey with 3-4 boats running  %) No problems AT ALL :-))
Title: Re: surface drives / rudders
Post by: triumphjon on April 26, 2010, 07:03:41 PM
thank you guys , at least us older folks know how to biuld a proper boat useing whatever timber we can find or afford ! its far more enjoyable than buying some ready made moulded tea tray from the net ! !  O0
Title: Re: surface drives / rudders
Post by: john54 on April 26, 2010, 07:35:37 PM
Thanks for the Thanks  :-))Hope you get it sorted after Some of the eh comments {:-{
Title: Re: surface drives / rudders
Post by: grasshopper on April 26, 2010, 11:16:02 PM
Whilst not the best engineering job in the world - made out from brass and old fruit machine bits it gives you an idea of what can be made - the only power tool used was a battery drill and a big soldering iron
(http://i121.photobucket.com/albums/o212/bigrasshopper/DSC_0157.jpg)
(http://i121.photobucket.com/albums/o212/bigrasshopper/DSC_0158.jpg)

mounted a little too low - but it replicated the relative position as it would have been on the original layout of this 37" 'Fletcher' fibreglass hull - the uj allowing a horizontal drive as opposed to angled - and powered by a 700 motor on 2 x 8 cell nicad packs on a series /parallel switcher made from micro switches (from fruit machines) giving off - half speed and cor blimey!

Previously the same hull had two solid shafts with geared 540's on 14 cells with the shafts coming straight out of the transom and home made rudders either side
(http://i121.photobucket.com/albums/o212/bigrasshopper/DSC_0160.jpg)

made from (yup!) fruit machine PSU brackets, cabinet hinges and other odds and sods
(http://i121.photobucket.com/albums/o212/bigrasshopper/DSC_0163.jpg)

All the above were made when basically, I was poor - had a wife, three kids and a huge mortgage - not the flashiest stuff in the world but back then (80's) it all wasn't available on the net, ready made or cheap.....Kids nowadays don't know their born

Title: Re: surface drives / rudders
Post by: Bill D203 on April 27, 2010, 12:12:34 AM
Don't kick your self. It looks OK and cost you very little so result all the way round.  Theres nothing wrong with having a go & learing from what you do as you go along. Been doing that for years now and i think i will for a bit longer to come.
 :-)) :-)) :-))
Title: Re: surface drives / rudders
Post by: martno1fan on April 27, 2010, 08:25:36 AM
Bill not wanting to rock the boat but futaba 2.4 fasst works well in fast boats as it uses spread spectrum tech that moves between many diff channles constantly.NOT all 2.4 systems work on this principle some just hop between 3 channels these channel hopping ones are pants and a great way to lose your fast boat  O0.So not all 2.4 systems work with fast boats.
Title: Re: surface drives / rudders
Post by: BJ on April 27, 2010, 08:13:47 PM
I've tried solid shafts as surface drive, trust me, it doesn't work...

Pick the bones out the three images - the Dateline Cherokee 2 IS a SOLID shaft boat and runs quite well with 25 as the grunt.
The diagrams were sent to me by a guy who has run fast electrics successfully on a solid shaft set-up based on piccies #21 & #68
Title: Re: surface drives / rudders
Post by: john54 on April 27, 2010, 08:22:45 PM
Thats what i meant in my replys it does work well  :-))Thanks for the pics Mate  ok2 sorted now i hope  :-)
Title: Re: surface drives / rudders
Post by: martno1fan on April 27, 2010, 09:24:43 PM
Might work well with leccy and small to medium nitro but it wont work well with 2 strokes,you wouldnt get the motor low enough nor far enough forward to get the angle shallow enough plus even if you could get the motor forward enough the balance would then be way forward.Me personally i wouldnt ever use a universal joint on anything fast,flexi drive is the best way and no more expensive than a solid shaft arrangement nowadays no matter what power plant you are using.Leave the universal couplings for the tugs and slow boats  O0.
Mart
Title: Re: surface drives / rudders
Post by: BJ on April 28, 2010, 10:46:31 AM
Might work well with leccy and small to medium nitro but it wont work well with 2 strokes,you wouldnt get the motor low enough nor far enough forward to get the angle shallow enough plus even if you could get the motor forward enough the balance would then be way forward.
Mart

Let's try for the third time to post this (1st - piccie too large, 2nd - You have already posted)

See the piccie. The engine is a Thunder Tiger 25 and the balance is OK. The boat is typical of a cigarette in the it heels on the turns.
Title: Re: surface drives / rudders
Post by: pompebled on April 29, 2010, 07:09:13 PM
Hi John,

A solid shaft and surface piercing drive in the Intercepter hull is no problem at all; I've just finished two 65 cm hulls with it and they run well.

The trick is to have a shaft that's as long as the correct position of the CoG allows for, the motor as far forward as possible, so the shaft exits the transom at a very shallow angle:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-arpro-700-ep-picture16278-ashoek.jpg)
The propnut should be between 10 and 13% of the hull length from the transom, in your case between 60 and 78 mm.

The motor should be as close to the bottom, only the watercooling coil should still fit.

I use a bulkhead for the motor to spread the load, a good thing in an ABS hull:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-arpro-700-ep-picture16371-motorspant01.jpg)
Topview:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-arpro-700-ep-picture16372-motorspant-02.jpg)

The motormount/coupling bell is a great benefit, no need to allign the motor and propshaft, this sorts itself out when the motor is bolted on, here in a 65 cm stepped hull:
(http://www.modelbouwforum.nl/forums/members/pompebled-albums-nood-uit-picture11958-bb02.jpg)

Mind you, these boats run on electrics, but nitro shouldn't be a problem either, the principles remain the same...

Here's a clip showing the boat in action: http://www.youtube.com/watch?v=HLcMharve1k
So, yes, it works!

Regards, Jan.
Title: Re: surface drives / rudders
Post by: john54 on April 29, 2010, 07:14:17 PM
We rest our case  ;)