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Old 13 September 2002, 22:35   #1
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A Tohatsu 90hp TLDI on a 6.5 mtr RIB

Can anyone help?

Please could I have some advice from all you experts out there. I was at the boat show today and have found and bought my first RIB, I am very interested in the great economy and technology in the Tohatsu 90hp TLDI engine. The power to weight ratio looks very good. This will be my first RIB and I will not be wanting to fly about just yet, can you tell me if this engine will do the job of giving me a reasonable performance. I am also looking at putting a 9.8hp reserve motor on, will this be sufficient on this size RIB? (Would this combination get me over to France on one of your trips?)

Thanks,

Please see this link for the technical details :- http://www.tohatsu.com/tech_info/tldi_faqs.html


Pete
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Old 14 September 2002, 03:12   #2
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I may be wrong, but a 90HP on a 6.5 Metre RIB would seem to be a little underpowered.

I have a 6.2 Metre Avon, with a 130HP on the back, and find this just about right. At our Powerboat School we have a 5.6 Metre Avon with a 90HP Mercury 4 Stroke, and this gives that RIB a similar performance to the 6.2.

It all depends what you want to do with the RIB, how many people will be on board, what equipment etc.

I know with my RIB that when I have had 6 or mre people aboard, especially in bad weater when they gather towards the stern for shelter, I have wished for more power!

As for your auxiliary, that should do the job OK. I have found this to be a matter of weight and size. On my transom, with the 130 mounted, there is only just room for a 5HP Honda auxiliary - anything larger and the main engine cannot turn fully.

This 5HP drives me on at around 6 knots in harbour - obvously much less in any wind or strong tide - but at least it gives a better option that getting the oars out!

The best answer to your question will be when you use the RIB - with however many people aboard, and all your kit, and se how she performs.

As for crossing th channel - join is in a fortnight and find out - but it should be up to the job - if you are.
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Old 14 September 2002, 03:42   #3
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Pete

What make is the RIB? What does the manufacturer say about using a 90hp engine with it? Can you sea trial the combination?

A 6.5m RIB with a 90hp outboard will certainly get you going, but if you find yourself with a heavily laden boat in deteriorating condtitions you might find yourself wishing for a bit more power.

If you are looking to use this RIB as a starter boat and then change to a bigger and/or more powerful RIB if you get the bug, then it will be fine. If it's more of a long term investment then you want to make sure that you're not going to outgrow it too quickly.

Having said that, even if you do eventually feel that a bigger engine would be better, you'll still have a lot of fun with a 90!

John
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Old 14 September 2002, 06:03   #4
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Hi,

Although I don't consider myself an expert, in a 6.5m rib I would not consider anything less than 130HP engine. I thing 150HP would be a nice thing to have.

I agree with the two previous answers that all depend in weight of the boat, usage ......... but 90HP sounds marginal for me.

I would also consider a classic two stroke outboard (a yam or merc). I am not still conviced for the fuel economy that the new high tech 2 stroke outboards are promising.

Certainly they use less fuel in specific RPM range and in ideal sea conditions, but according to my estimations and my rib usage they don't justify the extra cost (this is just my opinion).

I also feel more confident using a classic 2-stroke outboard in terms of reliability.

As an example (in my country) a Tohatsu MD90A-DI-EPTO costs 11.000 euro (list price, usually you get a discount).

On the other side a Yamaha 130BETOL costs 10.000 euros.

Regards


Dimitris
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Old 14 September 2002, 06:12   #5
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I had a 6.5m with a 150hp on it and this gave a good balance of outright speed and economy IMHO.

Is the RIB a Tohatsu one design? If so I could imagine them recommending the 90TLDI as if I recall correctly its the largest TLDI engine they do. It will be economic but load it up and you'll be wishing for more power! The Tohatsu brand RIBS are reasonable bits of kit in my experience.

I would not buy a "normal" Tohatsu (or Merc, mariner etc) of any size as fuel consumption of the TLDI/Optimax/Ficht/HPDI versions is significantly better - more than enough to justify the additional purchase price.

6.5 is quite capable of extended cruising - provided it has a decent deep v hull, good seats (jockeys) and a big enough fuel tank. And of course that you are up to it!

Cheers,
Alan
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Old 14 September 2002, 06:14   #6
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Re replies to is the 90hp big enough.

Thanks for the comments I have to bear in mind my budget and the fact that this will by my first ever boat. I would be using this for two people with perhaps one or two others once in a while. I certainly saw some great RIBS at the show, but just want to make sure that I will not be embarrased by total lack of power e.g. 20knts max e.t.c. Safety is a big concern, I want to ensure that I will be able to cope if the weather gets a bit bad, although I will certainly be only sticking to the coast like glue for the first few months. I guess the worst is that if I enjoy it I trade in the 90hp and get something bigger in a year or so. Part of my problem is I have been offered a package deal with only this engine (as it is already fitted), therefore the lack of flexibilty if I want to get it. Would it be easy to put a bigger engine on at a later date, and would that be expensive? I take on board all your comments and thank everyone for their views, it is great to find such nice people.

Regards to you all, and thanks again,

Pete
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Old 14 September 2002, 06:36   #7
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Quote:
Originally posted by Flanker
although I will certainly be only sticking to the coast like glue for the first few months.
This is not always a good idea as you will find rocks miles offshore.
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Old 14 September 2002, 06:56   #8
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Pete

I know from your email earlier that it is the Tohatsu one-design RIB that you are looking at. This combination should be fine -- these boats really shift with a 90!

I was really impressed when I trialed one when they were first launched a couple of years ago. They are quite a basic RIB, but are well made and good value with a decent hull.

If you do decide to upgrade to a larger outboard after a year or two it's a relatively simple job (although if the RIB bug really bites you may find that you come up with 101 reasons to justify getting a bigger RIB too!)

John
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Old 14 September 2002, 07:31   #9
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Thanks,

I have bitten the bullet after seeing responses and put a cheque in the post for this RIB. I understand that I will not be breaking any speed records but all in all it will do at the moment. I now need help in learning all I can to avoid any mistakes others have made in the past as new boat owners. Please see my new Thread 'Virgin Ribber needs advice'.

Thanks again to you all,

Pete
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Old 14 September 2002, 12:56   #10
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You might be alright with a 90. My thoughts are based on this: when they launch the 6m one design a couple of years ago with a standard 90 hp engine it had an astonishing top speed of 54 mph when tested by Rib International, achieved by having a slim hull with no excessive weight and tubes that just touch. Have a look at this test by RI.

http://www.ribmagazine.com/boat%20tests/TOHATSU6.HTM

And if you do want to change later on as JK said its quite straight forward and you should get a good price for the 90 as they are a popular size. Hope this helps. Pete
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