Mercury 115hp motor ??

Scotty · 28 October 2002, 13:36

Well I've made my mind up (I think) and I will fly to the UK on wed. to buy my rib. Its a Zodiac 550 pro open with lots of extras and a two stroke mercury 115 hp motor. Has anybody got comments on "mercury motors" ?

Thanks .

gavin · 28 October 2002, 14:02

I had a 50hp mercury excellent motor, relativly trouble free however in the motor I had Mercury had fitted a plastic cam on top of the gearbox the idea of this was to lock the motor in position when in reverse and netural, being plastic it simply wore away and I had to take the gearbox off to replace it.I dont think this is a feature of bigger Mercurys though.I liked the Mercury and would definately have one again, Greenpeace were in Dublin recently and they run a 200hp Optimax on one of their ribs,In Dublin Western Marine are both Zodiac and Mercury dealers,helpful and friendly.I have gone from Malahide to Bangor and back powered by a 70hp Mercury a really sweet motor about 3 years old and so far has given no trouble atall to the guy who has it, they appear to be popular motors and it sounds like you are going for a nice combination 5.5 zodiac and Merc, have you ever seen the military spec Zodiacs SRNM or the US coastguard Zodiacs with gun mountings and radar fitted, my first inflatable was a zodiac I still have it it is 1985 gavin

Scotty · 28 October 2002, 14:59

Gavin,
Thanks for the reply. I wanted the rib with the guns fitted but my wife say's she wont have it , anyway I think it may be against marina rules to keep machine guns on board. he he.

i am going to the UK for the boat as there is a big saving to be made even taking sterling into account.

Regards.

Pete7 · 28 October 2002, 19:06

The early four cylinder 115 hp Mercs were not very popular. They had a system for running on only two of the four cylinders below 1800 rpm. The idea was that they didn't need all four firing. Folk tried to say that this saved petrol, but it didn't. The other problem was that for water skiers, they didn't pull very well from low revs on two . If you have one of these engines they can be modified to run on all four. Think the later went back to running on all four cyls. Watch the fuel figures they can be expensive to run and are a very heavy engine. Had one on a Viper 5.25 and it didn't suit the boat. Switched to a 75 hp merc which although slower was much better balanced and had better fuel economy. Hope this helps. Pete

gavin · 28 October 2002, 19:48

Apart from the savings made with a trip to the UK you have so much more variety, although I wasnt with Tim when he bought the Hysucat, again it made sense to go to the UK, we have two other friends in Malahide marina both have brought boats back from the UK , not ribs but again for those very reasons, cheaper and more to choose from, will you keep the rib in a marina or trailer it do you think.We that is myself and Tim are in Dublin too we do a lot of trips up to Dublin port from Dunlaoghaire, to Malahide I also have a site up with info on the three islands out in the bay ,you can visit them easily in your new rib www.dublinsislands.com for some pics etc gavin

Powerboat · 28 October 2002, 20:34

We give out a lot of (free) advice to our training clients who are buying boats.

The first question we always ask them is what do they want to use the boat for ?

With that in mind, is there any particular reason why you are going 2 stroke ?

115 is a lot of power for a 5.5 . The fuel savings and increased range from a 4 stroke would be considerable if you planned on using it for cruising.

give us a buzz tomorrow if we can be of any help.

Best wishes ,

Stuart
www.powerboat.ie

jools · 29 October 2002, 02:44

I have the Mercury 90Hp 4 stroke on my Ribcraft 5.85. Very nice with cruiseing speed 25-30 knots and WOT of 38knots.

This is a carb engine infact exactly the same as the 75Hp but with bigger carbs.

The weight of the 75 and 90Hp is exactly the same which was one of the reasons for going for the 90. If I had gone for the 5.5m Ribcraft then I was recommended to pick the 75 - which is cheaper.

With my 90 I get about 1liter per mile (well its a bit better than that but I use this figure to be on the safe side!)

Jools

dimitris · 29 October 2002, 14:37

Hi,

I am using a 115 2-stroke merc on my 5 meter RIB.

It is a year 2000 model and I bought it new. The engine has
100 hours aprox.

My comments so far are

1) The engine never let me down till now.
2) It consumes quite a bit of fuel. I cannot say that fuel economy is one of it's main features. (Bear in mind that my rib is quite heavy though - The boat empty without fuel, equipment, and engine weights 450 kilos)
3) It is quite heavy for my 5M rib.
4) In bad weather, operating the engine in the RPMs where I have plenty and positive torque , gives me too many miles for the length of my boat in relation to sea conditions.
5) The response of the engine (even with five or six persons on board is fantastic.

Regards

Dimitris

nigelt · 29 October 2002, 15:09

I have the Mercury 115hp four stroke which is floorless!! (5.7m boat)

At about 2/3 throttle I can get 1.4 miles per litre but when going a bit faster I still get about 1 mile per litre.

Still quite new so nothing should have gone wrong yet!!

Nigel

Manos · 29 October 2002, 15:25

Dimitri , A 5 mtr RIB with a 115 bhp engine will go like a rocket (what pich prop you have on??).

SCOTTY

For your benefit now please note that I use to have a GEMINI 5.05 and I had a 75 bhp very old Mariner (1991) on board with very many hours trawling and cruising. The boat and engine went like a dream. With a 19" AL original prop it was doing 45 knots @ 5,500 revs full trim with 2 people onboard and 140 ltrs of fuel, full load and light chop in the Aegean and with a 17" AL prop it was giving 38 knots @ 5500 revs full trim same conditions as before, however as you would expect acceleration and pull was much much better than with the 19" prop.
The engine excpet having problems with the trim motor (had to repair it every summer because the new one comes with the bracket and costs as much as an engine more or less) nothing else happened and I sailed the boat a lot.
Consumption for the 75bhp Mariner about 1 ltr/mile (normal staff) doing 3500-4000 revs with both props.
In have now a 7mtr boat with a 200bhp Yam VMax different ball game altogether (F A S T VERY VERY VERY F A S T 65knots @ 5800 revs full trim and light load and 21" pich prop!!- will change it now for a VIPER 23" and will try also a 25" see what happens).
Now for the benefit of the thread I believe that all two stroke engines these days have more or less same endurance and reliability unless of course you are lucky enough to get the 'Friday the 13' engine. Then it doesn't matter what make you've got.
A Merc or Mariner are good, very good infact.
I have heard bad comments about the electrics and fuel supply for the Envinrude Fihts but never owed one.
Finally, knowing that all Mercs and Mariners suffer from trim problems, I would make just sure that the trim motor hasn't been opened and is in tip top condition. If this wasn't the case I wouldn't touch one. As I said it costs faaar tooooo much to change it and repairing it is not an option unless one is desparate (like I was).
Hope this little wafle could assit .

......and Scotty since you are in Greece why don't you pass by and check out the Falcon is MUCH MUCH better and more competitively priced that the Zodiac.

Manos

Scotty · 29 October 2002, 16:17

Quote:

Originally posted by Powerboat
We give out a lot of (free) advice to our training clients who are buying boats.

The first question we always ask them is what do they want to use the boat for ?

With that in mind, is there any particular reason why you are going 2 stroke ?

115 is a lot of power for a 5.5 . The fuel savings and increased range from a 4 stroke would be considerable if you planned on using it for cruising.

give us a buzz tomorrow if we can be of any help.

Best wishes ,

Stuart
www.powerboat.ie

I'm going for two stroke because it's on the boat ! The previous owner has only put up 30 hours in the one year he had the boat. And as the boat will be used for fun and as a "Daddys Toy".... my kids words, I'm not too concerned about economy. I hope I dont regret saying that.

batfalcon · 29 October 2002, 17:35

I'm sure that you won't (regret it). Since the engine is in good condition (as I understand it must be in excelent), you don't have to go for a 4 stroke. I have this very engine for the past 5 years, on a Bat 9 Falcon X boat. Bought it new and it's running like silk. Needless to say that I don't have to crank the engine twice to fire her up after winter storage. Fuel consumpion 1 litre/mile on MUCH heavier than usual boat.
To give you an idea, completely empty boat, without tanks, A frame and accesories is 475 kg. I calculate the weight of the whole combination about 950 to 1050 kg with 2 adults and 150 lit of fuel.
With 19'' prop the engine tops at 5000rpm (I told you that the Bat is heavy). I shall put a 17'' to climb at the 5250 which is optimum for this engine.

gavin · 03 November 2002, 10:55

Scotty did you buy the rib , or did the deal not happen cheers gavin

Scotty · 03 November 2002, 11:04

Gavin,
I did the deal last wed. I will do a money transfer to their bank tomorrow monday and then I'm getting a guy to trail the boat from Kent to Fishguard to the ferry for £300 stg. Being the lazy git i am then all I have to do is collect from Roslare and back to Sutton.
Regards,

Luke.

TIM · 03 November 2002, 21:01

Well done...... I look foward to meeting up in Dublin Bay, going up the Liffey is good fun,

Powerboat · 03 November 2002, 21:21

Dublin Bay and the Liffey are really fantastic now especially at night.

Our gang from the School have been running Advanced powerboat courses there over the last few months .

Much more glamourous at night than our usual haunt off of the West Coast !

I am still wrestling with my conscience over the engine choice for our new boats (Honda may be winning the coomon sense battle !)

Best wishes and well wear Luke !

Stuart
www.powerboat.ie

Scotty · 04 November 2002, 08:54

Quote:

Originally posted by Powerboat

I am still wrestling with my conscience over the engine choice for our new boats (Honda may be winning the coomon sense battle !)

www.powerboat.ie

Re Honda !!

I hope you get treated better by "Honda" than some of my bike mates ! They dont like warranty work too much !

Tiger · 04 November 2002, 17:38

Honda have a mixed bag on performance of custermer service.

The engines are ok, but customer service has been dreadfull for HQ (not the dealers) in a few (rare) cases I know of.

Honda HQ need to pull socks up or customers will walk!

As I said good product though

tiger

tinus · 08 January 2006, 12:43

Quote:

Originally Posted by Pete7

The early four cylinder 115 hp Mercs were not very popular. They had a system for running on only two of the four cylinders below 1800 rpm. The idea was that they didn't need all four firing. Folk tried to say that this saved petrol, but it didn't. The other problem was that for water skiers, they didn't pull very well from low revs on two . If you have one of these engines they can be modified to run on all four. Think the later went back to running on all four cyls. Watch the fuel figures they can be expensive to run and are a very heavy engine. Had one on a Viper 5.25 and it didn't suit the boat. Switched to a 75 hp merc which although slower was much better balanced and had better fuel economy. Hope this helps. Pete

Pete
Where can I get hold of this modification. I have one of those motors and I what it to run on all 4 from the begining

Pete7 · 08 January 2006, 15:06

Martin Stitt, the Mercury dealer in Larne, Northern Ireland did it for me, how I have no idea since it came modified, but obviously there is a cut out switch in the ignition. How about having a chat with your nearest Mercury dealer. Check to see if the later models have the same system if not you could possibly find a later ignition system.

Pete