Reply
 
Thread Tools Search this Thread
 
Old 06 April 2002, 03:32   #11
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
Mike, the Merc 90 two stroke should be fine for the boat as its the same weight as the 75 hp, the difference is is probably in the carbs and ports.
Fuel should aslo be about 6 uk gallons per hour slightly less if your lucky because I doubt if you are going to use full power. A nice stainless steel prop will improve performance if you can guarrantee not to run aground (see previous posts on props) Not sure how big a US gallon is but, 1 uk gal is equal to 4.5 litres, so you will be using 27 l per hour at speed. Probably easiest explained by one red merc fuel can every hour or just under anyway. But please take two at least, with seperate fuel lines heavy cylinders and careless divers do not go well with rubber pipes. The merc will thank you if you have a good filter as well. Merc do one but the better option is a CAV glass bowl and filter that normally fit diesel engines. Your not supposed to use with petrol but they work fine and have a very fine filter and you can see the water or colour of the fuel. The standard engine one isn't really up to it and esily over welmed.
Additional fuel always useful when you have lost a diver and have to search for an hour. We learnt that lesson watching another rib in Northern Ireland many years ago. Ended happily after five hours when the divers where found 20 miles away Great to here your using metric, esp for diving the calculations are soooooo much easier for air consumption and pressure etc. Petrol here in the UK is 73p a litre at a garage and we saw 93 p a litre ! at a waterside pump over Easter. The reason its so expensive is 90% is tax
20 UK gallons will cost 65 and we can use 30 easily in a days diving, plus the 2 stroke oil. Running about 1.7mpg with the 150 Mariner at the moment.
Do please fit an echosounder its the only thing that stops you running aground and worth its weight in gold. Also gives you an accurate depth prior to deploying divers, and lastly it finds your wrecks. Lowrance or Eagle have an excellent rep with UK divers and just work year in year out. But choose carefully the more expensive the greatr the power and better bottom definition. Its al down to power of the unit and it really is quite suprising what the more powerful sets will show up. I have the Lowrance LMS 350a which is great and miles better than budget sounders. Hope this helps and safe diving, Pete
__________________

__________________
Pete7 is offline   Reply With Quote
Old 06 April 2002, 05:13   #12
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
Mike, here is the link I was looking for:
http://www.outhill.com/ its a bit slow and took a couple of attempts to load, regards Pete
__________________

__________________
Pete7 is offline   Reply With Quote
Old 06 April 2002, 12:13   #13
Member
 
Country: USA
Town: Portland
Make: Polaris
Length: 5
Engine: 90hp- 2stroke!
Join Date: Apr 2002
Posts: 15
Ok, one last question and I'll be done with this thread! I promise!

As I have calculated, fuel is is roughly 1/3 the cost of where most of you are. (more or less) Yes, I feel lucky! To this end, I was planning on buying a 2 stroke 90hp. I might still be swayed to the 4 stroke 90hp, but I'm not sure.

Of course the added benefit is that they are cleaner and more fuel efficient. Of course I would be getting a Merc, and they are still a little new in this. (Yam Suzie, or Honda are priced out of my range, the Merc is the only one that is ALMOST within pricing grasp) The Merc 4 stroke will cost me about 4200 pounds. That is about 20% more than the 2 stroke. Of course the 4 stroke also weighs 80 more pounds.

Is it worth it with longevity and performance issues if the fuel consumption is not factored in? Until April 15th, there is a extended warranty on these motors that gives 5 years of coverage to the original owner.

Input is appreciated.
__________________
playspot1 is offline   Reply With Quote
Old 06 April 2002, 14:38   #14
RIBnet supporter
 
Brian's Avatar
 
Country: UK - Isle of Man
Town: Peel, IOM
Length: no boat
Join Date: Nov 2000
Posts: 2,277
RIBase
My humble opinion is that if you can save 20% by going 2-stroke AND save 80lbs in weight, then surely it's a no-brainer?
I think all up weight is the true gating factor here.
__________________
Brian is offline   Reply With Quote
Old 08 April 2002, 09:08   #15
Member
 
Country: Denmark
Town: Copenhagen
Boat name: Nemesis
Make: CAPE 79
Length: 8m +
Engine: Suzuki 250 4 stroke
Join Date: Dec 2001
Posts: 252
Send a message via AIM to Rene Send a message via MSN to Rene
RIB and Engine size

Hi

About the engine sice that Pete was talking about. I bought my RIB from Pete, with a 115 HP Yamaha. And with 6 divers 2 tanks each, you will have to place that right in the boat to get it "out of the hole" even with the 115 HP.

I would recommend a console !!, if you can get hydralic steering it's a nice touch

Rene
__________________
Rene is offline   Reply With Quote
Old 08 April 2002, 09:29   #16
Member
 
Country: Denmark
Town: Copenhagen
Boat name: Nemesis
Make: CAPE 79
Length: 8m +
Engine: Suzuki 250 4 stroke
Join Date: Dec 2001
Posts: 252
Send a message via AIM to Rene Send a message via MSN to Rene
Ups

Sorry about this.....

This was meant as a reply to "RIB Engine sizing help!"

Must have pressed the wrong button.

Need to look more on my mouse movement

Regards
Rene (Sorry about this) Nielsen
__________________
Rene is offline   Reply With Quote
Old 08 April 2002, 13:32   #17
Member
 
Country: Greece
Town: ATHENS
Boat name: SUN KISS II
Make: Nuova Bat 9 Falcon -
Length: 5m +
Engine: Outboard Mercury 115
Join Date: Jun 2001
Posts: 639
Send a message via Skype™ to batfalcon
Playspot1,

I didn't realize that you were talking about jets. As far as prop engines I do have my doubts. A friend of mine had an accident the year before last due to a broken screw. The one that bonds the engine with the flexible rod from the steering wheel. When the screw broke the torque of the engine turned it all the way to the left forcing the boat to do a sharp left turn and throw the skipper in the sea. Luckily he had his kill cord attached so the boat stopped after making a full circle. He was twice as lucky as the boat didn't hit him making the 360 turn.
Without the steering system he had to attach something on the engine in order to steer the boat. Using his hands was impossible to hold the engine straight so he had to use something like a steering rod. Using some ropes he managed to attach his fish gun on the engine's cover and made his way back, controling the remote control's lever by his foot.
So I think that at the time of the acceleration it is much to difficult to keep the engine alined. Maybe it's a little easier when the boat has a constant speed, after it has been out of the hole.
__________________
Michael a.k.a "Bat Falcon"

batfalcon is offline   Reply With Quote
Old 08 April 2002, 16:30   #18
Member
 
Pete7's Avatar
 
Country: UK - England
Town: Gosport
Boat name: April Lass
Make: Moody 31
Length: 9m +
Join Date: Aug 2001
Posts: 4,850
Rene, what are you doing about the engine, you were thinking of changing ?

This might be of interest:

http://www.outboardsdirect.co.uk/products.html

Regards Pete
__________________
Pete7 is offline   Reply With Quote
Old 08 April 2002, 19:40   #19
Member
 
Country: Denmark
Town: Copenhagen
Boat name: Nemesis
Make: CAPE 79
Length: 8m +
Engine: Suzuki 250 4 stroke
Join Date: Dec 2001
Posts: 252
Send a message via AIM to Rene Send a message via MSN to Rene
Hi Pete

Well I was thinking about that, but I talked to some people from Yamaha on the boat show here in Copenhagen, and they had one of there people to have look it over, and now the problems are gone....

I had another shop to look at it last year, and after they had it in for service, it was a nightmare to get it started... I toold the Yamaha people about this on the boat show and they must have called the shop where I had the boat in last year, because Yamaha called me and told me that they would look it over for free..

I don't know what they did to it, but I didn't pay anything, and now the problems are gone.

So the next issue here is to get a bigger boat , I just have to convince my wife about that too

I would like something like the 8.5 meter scorpion, but I'm not settled on anything yet.

They Osprey is a super RIB, but with 6 divers it's getting crowded

Regards
Rene
__________________
Rene is offline   Reply With Quote
Old 08 April 2002, 23:54   #20
Member
 
Country: USA
Town: Portland
Make: Polaris
Length: 5
Engine: 90hp- 2stroke!
Join Date: Apr 2002
Posts: 15
Batfalcon,

Actually I WAS talking about prop drive. I used the example of the jet, but I've done both prop and jet in large engines. Really the whole key is probably the torque of the engine steerer tube. (if that's what you call it) If the engine is "loose" on the back of the boat, it's not really a big deal with a steering wheel, but it could be with a tiller. If the engine is snugged up a bit, it makes it easier to hold. Also, realize that thed larger the motor, generally the longer the tiller. This starts to use a longer leverage principle, and becomes very manageable, even with a large prop driven motor.

I have run boats that are very loose on the back, and swing freely from side to side. (You know, the guy who is trailering his boat without hit O/B fixed, and every turn, or lane change, the engine swings from one side to the other. This does make it more difficult, as you have to exert more force. This engine looseness is pretty irrelevant with a steering wheel, as the steering box makes it very easy to hold the engine aligned correctly. Since it is common to have between 31/2 to 4 complete turns of a wheel lock to lock, very little change happens with a pretty good turn of the wheel. With a tiller handle, very little engine shift prompts a significant change in course angle. Subsequently, making the engine more difficult to turn takes away the hazard associated with a tiller, while not reducing steering input. Running full out with a tiller, you can change course probably 30 degrees with only a 6 inch shift of the tiller.

Now, don't get me wrong, thanks to you, and others advice I will be putting remote steering on my boat. This is more so because of my concern of the weight to power ratio of the craft. Unburdened, in a medium chop at full speed, you would have nowhere near the control with a tiller that you would with a steering wheel. The problem would come from hitting a wave and skipping sideways a bit, while trying to hold your body and tiller fixed so as not to over steer the craft. I think I would have difficulty with this. With a larger RIB, one that wouldn't have a tendancy to bounce laterally as much, and weighed more, I would still consider a tiller a fine alternative, but not a craft this small.

As far as your friend goes, I can imagine that it WOULD be extremely difficult, almost impossible to control an engine not set up with a proper style tiller, especially if is swung "loose". Properly set, the torque of the engine shouldn't make the engine move off course by itself. Of course if you hit a wave, untended, the engine is bound to swing one way or another. For safety sake, I never let go of the tiller, but typically, once running, my hand is just resting on the handle. The throttle should stay put, as should the engine.

Thanks for the help, I do appreciate it.

Mike
__________________

__________________
playspot1 is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 12:17.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.