5m rib, 60hp..2 stroke or 4 stroke?

Gray · 14 February 2006, 15:16

I've been looking around for my 1st boat and the 5m mark looks good for me. Ive seen two boats, both just under 5m, one with a 60 2 stroke and one with a 60 4 stroke. Whats going to be the main differences between the two i.e. performance and fuel usuage etc?
Thanks!

Jono Garton · 14 February 2006, 15:55

Hi

Depending on the rib about .5 litre per mile on the four stroke and 1 litre per mile on the 2 stroke (unless direct injection), in my experiance.

On a 5m Humber with 60hp Four Stroke we were getting about 35 knots, which seems very fast in a little boat.

Jono

Gray · 14 February 2006, 16:04

One is a ribcraft and one is a tornado. I personally only have experience on a tornado and am under the impression their deep v makes for a soft ride. However ribcraft seem to me to be the boat of the moment for that size in terms of structural reliability. Any thoughts?

Both boats are getting 35 knots which is plenty.

GB

Jono Garton · 14 February 2006, 17:26

What about a nice new humber -

http://www.rib.net/forum/showthread.php?t=12909

Tim M · 14 February 2006, 18:43

The portsmouth uni rib is a 4.8 ribcraft with 60hp mariner 4 stroke. It's a very well built, stable and fast little boat.....

Gray · 15 February 2006, 14:36

Jono...nice looking humber, a little above my price range im afraid but thanks anyway!

Tim, the ribcraft, whats it like when it gets a bit lumpy in the solent. Is it wet and dry and does it slam much....

GB

Jimbo · 15 February 2006, 19:31

Quote:

Originally Posted by golfbravo06

Tim, the ribcraft, whats it like when it gets a bit lumpy in the solent. Is it wet and dry and does it slam much....

For a 4.8m, it's unbelievably dry! She is without a doubt the best sub 5m boat I have ever been on.

Given the hull shape, she handles seas well - however she is fairly light, so does get a little twitchy at high speed (I've had her at 37kts with a 60hp 4smoke bigfoot). Build quality is superb.

If I am ever fortunate enough to be buying new - Ribcraft are definitely top of my list!

You'd be more than welcome to a spin in the Uni boat if you're ever down this way.

DJL · 17 February 2006, 22:08

I would definitely go for the 4-stroke. 2-stroke technology in the range around 60HP is still pretty basic.

You can expect to get around 30-40% better fuel economy with a 4-stroke depending on how hard you push the engine (assuming a carb 2-stroke not an Evinrude Etec, Nissan TLDI etc). Performance will be pretty similar between the two.

codprawn · 17 February 2006, 22:38

Quote:

Originally Posted by DJL

I would definitely go for the 4-stroke. 2-stroke technology in the range around 60HP is still pretty basic.

You can expect to get around 30-40% better fuel economy with a 4-stroke depending on how hard you push the engine. Performance will be pretty similar between the two.

Not from the Tohatsu TLdi it's not!!!

Gray · 18 February 2006, 17:13

thanks for the input people...

Jimbo do you know what year the uni's boat was made and how well are the tubes etc fairing up to being used by a university, Soton Institutes boat always seemed to look fairly worn out. Thanks for the offer by the way ill pm you about it.

GB

Rogue Wave · 18 February 2006, 17:13

Quote:

Originally Posted by DJL

I would definitely go for the 4-stroke. 2-stroke technology in the range around 60HP is still pretty basic.

You can expect to get around 30-40% better fuel economy with a 4-stroke depending on how hard you push the engine (assuming a carb 2-stroke not an Evinrude Etec, Nissan TLDI etc). Performance will be pretty similar between the two.

Never trust a teenage mechanic!

doesn't most 4 strokes carry a weight hendicap, have the 4 strokes got the low down grunt of a 2 stroke.

I've just been out on a 5 metre with a 75 hp 4 stroke and I am realy disapointed with its lack of snap. It's quiet though and frugal.

I note you are from Southampton. I have a Gemini 5 m with a Merc 75 4 stroke and an Avon 5.4 with a 70 Tohatsu.

neither are for sale but you are welcome to try em both out and see what you think! ( you pay for the fuel)

of the two boats I'd go for the Ribcraft this craft had a very good record in the old RB4 challenge

Gray · 18 February 2006, 17:21

Cheers for the offer of trying them. Ive was reading another thread and am i right in thinking its your place this side of Northam Bridge?

Rogue Wave · 18 February 2006, 17:27

now that depends on where you are. We are part of the boatyard that is at the Northam end of Northam bridge next to Coalporters rowing club.

Gray · 18 February 2006, 17:29

yep the stadium end, what do you charge for storage...actually...will you be around anytime tomorrow?

Rogue Wave · 18 February 2006, 17:35

Yep i'll be there from 09:00 hours and we are very reasonable. It's the first unit in the boat yard. There is a Landy 110 and a fork lift just outside

DJL · 18 February 2006, 17:38

Quote:

Originally Posted by Rogue Wave

Never trust a teenage mechanic!

doesn't most 4 strokes carry a weight hendicap, have the 4 strokes got the low down grunt of a 2 stroke.

I've just been out on a 5 metre with a 75 hp 4 stroke and I am realy disapointed with its lack of snap. It's quiet though and frugal.

Actually Mr Wave I had the pleasure of upgrading the engine on my 4.7m RIB from a Mercury 60HP 2-stroke to a Mercury 60HP EFI 4-stroke (10kg difference in weight). In my case I saw fuel consumption improve by 30-40%, pretty much what they state in the literature. Furthermore, performance wise they were pretty much identical, in my case i gained a few knots on top end speed with the 4/.

I suspect the poor performance you experienced with the 75HP 4/ was due to its horrible power-to-weight ratio (same block as the 90 and 115) and its lack of fuel injection.

Gray · 18 February 2006, 17:41

ok cheers, i'm going to try and come round about lunchtime.

Rogue Wave · 18 February 2006, 17:54

Quote:

Originally Posted by DJL

Actually Mr Wave I had the pleasure of upgrading the engine on my 4.7m RIB from a Mercury 60HP 2-stroke to a Mercury 60HP EFI 4-stroke (10kg difference in weight). In my case I saw fuel consumption improve by 30-40%, pretty much what they state in the literature. Furthermore, performance wise they were pretty much identical, in my case i gained a few knots on top end speed with the 4/.

I suspect the poor performance you experienced with the 75HP 4/ was due to its horrible power-to-weight ratio (same block as the 90 and 115) and its lack of fuel injection.

How can you put pleasure and 4 stroke in the same sentence!

Jimbo · 18 February 2006, 20:29

Quote:

Originally Posted by Rogue Wave

I've just been out on a 5 metre with a 75 hp 4 stroke and I am realy disapointed with its lack of snap. It's quiet though and frugal.

I thought she was pretty nippy actually, obviously not a 2 stroke levels, but fairly brisk all the same.

Quote:

Originally Posted by Rogue Wave

I have a Gemini 5 m with a Merc 75 4 stroke and an Avon 5.4 with a 70 Tohatsu.

No you don't, you have a Gemini 5.5m with a Mariner 75 4 Stroke, and an avon 5.4 with a 90 tohatsu.

Quote:

Originally Posted by golfbravo06

Jimbo do you know what year the uni's boat was made and how well are the tubes etc fairing up to being used by a university, Soton Institutes boat always seemed to look fairly worn out. Thanks for the offer by the way ill pm you about it.

Golf Bravo - yes, she was made in 2005, as I ordered her! She has thus far proved excellent - she still looks brand new after 60 hours since August.

Look forward to your pm.

Rogue Wave · 18 February 2006, 20:38

Quote:

Originally Posted by Jimbo

No you don't, you have a Gemini 5.5m with a Mariner 75 4 Stroke, and an avon 5.4 with a 90 tohatsu.

oh yes! you are correct oh windy one.

To tell the truth there were 5 adults on the boat at the time, and yeah she's not bad for a four stroke, but I like 2 strokes and I thought it would be fun to give DJL a prod. (who is one stoodent I have a lot of time for!).