Which is the best for steering: Steerable outdrive, in line rudder or offset rudder

[lucozader]

what are the differences ?

which is the best ?

[sailr]

Steerable outdrives have a universal joint that robs power and is suspect to hold up under the power we apply with brushless motors. I'd 'steer' (pun intended) clear of them.

In line rudders used mostly on CAT hulls and offset on V hulls.

Bottom line, use what works for you.

[Fluid]

The vast majority of R/C race boats use an offset rudder. Part of the reason is because they turn mostly to the right, with few left-handed turns. Another reason is because the prop wash hits the in-line rudder and can cause the boat to wander and twitch - and it also causes considerable drag.

Steerable outdrives are mostly found on entry-level, low performance models. They provide quicker turning at low speeds and 'look cool'. But as stated above they are more fragile, cause a lot of drag, and will usually cause the boat to hook badly in turns if the speeds are increased much above stock.


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[lucozader]

why do cats

why do cats tend to use inline rudders ?

[Jesse J]

I have tried a flex drive through my steerable drive in my miniV - yet to try it out. BUT this technique (which I learned here) removes the drag/weak link that the Ujoint represents. Should be a good compromise, but not sure how well it would work on larger apps. I have lots of experience with the beloved spinout on larger boats (e.g. the electroVee). I have since converted all mine to off set rudder..... with one exception.

My 27" balsa cat has the black inline rudder system I got from OFE and I love it. Granted it does exhibit the instability noted in posts above, but one feature I have come to love is that it acts as a keeper in that if my shaft breaks, or the coupler lets loose... I don't lose the whole caboodle. The other boon is about as equal behavior in left / right turns. And since I haven't lived in a place yet where there are others wanting to race, I have enjoyed the sporting side and like to be able to turn the same left/right.

Not sure why you say "cats tend to use inline rudders" I don't know that I would make that generalization, becuz I would say most cats "tend" to use offset - speed and stability at that speed. All cats have to slow for the corners (unless they are mean machines - rightly named), and their advantage is greater speeds on the straights.

[Fluid]

...I would say most cats "tend" to use offset - speed and stability at that speed. All cats have to slow for the corners (unless they are mean machines - rightly named), and their advantage is greater speeds on the straights.

You were okay until you said "all cats have to slow for the corners". That is emphatically not true for all cats, just for most scale designs. Full-scale offshore cats are narrow because they race on rough water and turning is not as important as top speed. They slow 'way down on the full-scale corners, or they roll over - sometimes they do both.

Most non-scale model cats turn from well to very well. All the Aeromarine cats I have or have seen can run full-throttle into the turns, ditto for the AC and Stryker cats. The H&M SuperCats turn great too, but unlike most German designs they are not scale models of real offshore boats.

A good racing R/C cat turns inside any mono or hydro; I know as I've raced them for decades and have won many races by cutting inside of monos and hydros in the turns. Cats are generally not as fast as a similarly-powered hydro but are as fast or faster than a mono. I love cats - but that's just me.



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[Fruity]

The MHZ outdrives are good units, we have the S6 on a 56"Apache with a Quckdraw motor, handles the power without any problem at all.

They do not use a uni or cv joint, they use the flex shaft to allow the steering, it is supported by a bearing.

The only problem I have had is the radius of the turn in the flex shaft was too tight and caused a break, I did two things to fix it. 1, limited the steering throw, 2, moved the fixed point of the flex shast further into the boat (forward), this allows the bend to occur on a more gentle radius.

These outdrives look ace, handle well, are very easy to adjust the trim on (you can buy a powertrim servo actuated option), and allow awesome turning even in vaery large boats. you just back the throttle off, dip it into the turn, then carefully bring the power back --- Turns on a dime.

Check out the MHZ wesite, very nice stuff, I think they even have a smaller modle than the S6 nowdays.

As always, it is personal prefernce and suited to what you want from your boat.

Cheers....Tim.