Engine sizes

Bigj · 17 January 2008, 14:59

Can anyone advise on the minimum size of engine that would provide adequate performance on a 5m Chinook please? High speed isnt a big requirement as the boat will be used on rivers and estuaries initially.

Joe

ian parkes · 17 January 2008, 21:42

Come on Nos4 how is that little 2.2 as an aux on yer rib.

Nos4r2 · 17 January 2008, 22:17

Quote:

Originally Posted by ian parkes

Come on Nos4 how is that little 2.2 as an aux on yer rib.

Haven't fitted the aux bracket yet

Course, it all depends on what you think is adequate (actress, bishop etc...)

ian parkes · 17 January 2008, 22:31

Quote:

Originally Posted by Nos4r2

Haven't fitted the aux bracket yet

Course, it all depends on what you think is adequate (actress, bishop etc...)

I was looking at my transom working out the best way to fit the Aux . It looks like with the main engine tilted right up the aux may clamp next to it . I couldn't run like that but lifting it on and off is the intention anyway . Its only the steering ram that is in the way of the clamps when the main motor is lowered .

Think Iam going to buy a new motor now , £200 plus for 10 yr old motor is too much IMO .
It has to be iether 3.5 tohatsu or 2.5 suzuki 4 stroke both same wieght and price , would prefer the suzuki but unsure if it will have as much go as the tohatsu . Iam thinking 4 stroke torque against the 2 stroke revs for slow speed use ?

Markyboyo · 18 January 2008, 00:52

If you want to be able to get on the plane with 3-4 up I think you'd need a 50HP mimimum though you may find a 60 to be more ecconomical as it wouldn't be working quite so hard.

Bigj · 18 January 2008, 09:04

Quote:

Originally Posted by Markyboyo

If you want to be able to get on the plane with 3-4 up I think you'd need a 50HP mimimum though you may find a 60 to be more ecconomical as it wouldn't be working quite so hard.

Thanks for that. The DT60 is no more and I have been offered a low hrs (20) 30hp engine complete with all the ancillary equipment. I am aware that it is half the power and cant expect the same performance as the 60 but wondered if it would be just too underpowered for this boat as to make the purchase not worthwhile?

Joe

9D280 · 18 January 2008, 10:44

Bigi,

As Marky says, it might struggle 4 up, BUT, with the correct prop you might be OK, if a little lethargic with the top speed.

Many years ago I drove a 5.4m Searider which was Ex twin 30. One engine was away for a service or something and the boat planed (just!) on the single 30 with (I think) 4 or 5 aboard.

What's this 30 Hp engine? If it's a Suz I think I know someone with a spare 12" prop if it labours....

John Kennett · 18 January 2008, 11:21

Quote:

Originally Posted by Bigj

I have been offered a low hrs (20) 30hp engine complete with all the ancillary equipment.

It might be usable in sheltered water, but I reckon it would be a rather unsatisfactory experience.

I'd look for at least a 50 or 60. It would be well worth it in the long run.

Have fun!

John

Bigj · 18 January 2008, 11:31

Thanks for the valued advice guys, I think I will look at something a little larger. Cheers.

Joe

ian parkes · 18 January 2008, 18:56

Sorry Joe
I didn't mean to hijack your thread , somehow I thought you were asking what size minimum for an aux motor doh

There seems to be a reasonable choice of used motors about in the size you need ,or so it seems while I have been looking for small one anyway .

Good luck

Nos4r2 · 18 January 2008, 22:37

Quote:

Originally Posted by ian parkes

I was looking at my transom working out the best way to fit the Aux . It looks like with the main engine tilted right up the aux may clamp next to it . I couldn't run like that but lifting it on and off is the intention anyway . Its only the steering ram that is in the way of the clamps when the main motor is lowered .

Think Iam going to buy a new motor now , £200 plus for 10 yr old motor is too much IMO .
It has to be iether 3.5 tohatsu or 2.5 suzuki 4 stroke both same wieght and price , would prefer the suzuki but unsure if it will have as much go as the tohatsu . Iam thinking 4 stroke torque against the 2 stroke revs for slow speed use ?

How would you steer it?

Pete7 · 18 January 2008, 22:50

Quote:

Originally Posted by Nos4r2

How would you steer it?

How about two of them

Nos4r2 · 18 January 2008, 23:09

Quote:

Originally Posted by Pete7

How about two of them

Or 3?

ian parkes · 18 January 2008, 23:20

I figure I would steer it using the tiller handle on the aux , maybe need an extension handle ? At least it would reduce the drag of the main motor in the water

Think I will have to just get the motor then work it out from there . There's Not much time left for buying the little 2 strokes .

Pete7 · 18 January 2008, 23:21

Quote:

Originally Posted by Nos4r2

Or 3?

oh one as a bow truster, great idea, think we could market it

BruceB · 18 January 2008, 23:35

I used to leave the main outboard down and steer using that as a rudder.
It was a bit hard to trun sharply but it worked well enough.
I wouldn't recommend the TS Tohasu 3.5, mine was forever seizing up and having to be stripped to get it working again. It eventually died electrically completely after only running less than 5 hrs in two years and I scrapped it to buy a 2.3 FS Honda last year. This has been fantanstic so far and has been very reliable.

ian parkes · 18 January 2008, 23:41

Quote:

Originally Posted by BruceB

I used to leave the main outboard down and steer using that as a rudder.
It was a bit hard to trun sharply but it worked well enough.
I wouldn't recommend the TS Tohasu 3.5, mine was forever seizing up and having to be stripped to get it working again. It eventually died electrically completely after only running less than 5 hrs in two years and I scrapped it to buy a 2.3 FS Honda last year. This has been fantanstic so far and has been very reliable.

That doesn't sound good news , i thought it was a well respected motor .

Maybe you can tell me Bruce how much more power did the tohatsu have than the Honda , did you ever use it on your rib for a donkey engine ?

Pete7 · 19 January 2008, 16:35

Quote:

Originally Posted by ian parkes

That doesn't sound good news , i thought it was a well respected motor .

They are, we have the 3.5 hp Johnson version (its white paint instead of grey) pushes the tender along nicely, never serviced and just chucked in the garage at the end of the season. Might be a little small for a rib, see if you can borrow one first to ty it.

Pete

BruceB · 19 January 2008, 19:10

I found the carb linkages would seize up making it impossible to start until the whole thing was stripped down and freed off.
Eventually after two years with the only use being started occassionaly and the testing after each repair, it died completely and the electrical system, what little there is sealed, was Gubbed and beyond economic repair.
It just didn't like to be on the transom of a RIB as the salt water seems to corrode the alloy parts.
The Honda seems to be standing up to the abuse much better.
Both were used as Aux motors and both pushed a 5.3m rib along at approx 4knts, neither was faster than the other.

Locozodiac · 19 January 2008, 19:14

[QUOTE) That doesn't sound good news , i thought it was a well respected motor .

By 1 dissatisfied user you cannot tell whether a brand is bad news, for instance in BVI from 12 engines I have personally seen, 10 were Tohatsu's, 1 Mercury and 1 Yamaha. And you see hundreds of them in mostly ribs cruising all day long as yacht tenders with excelent results.

http://www.pbase.com/locozodiac/image/82593974
http://www.pbase.com/locozodiac/image/82739127

Maybe the engine was poorly kept, electrical parts died prematurely due to humidity and very poor usage in such a number of years. Should use a proper marine grease to have all linkages working properly. A outboard must be started/used constantly.

Happy Boating