Honda 45 4 stroke on 5.5m Rib

Thepooster2002 · 11 October 2003, 21:10

I'm thinking of changing my 4m Avon for something a bit bigger say 5 - 5.5m, I would like to keep my outboard though anyone know if this engine would be powerfull enough for that size hull, consider also the weight of 4 divers/kit.

Thanks

zod550 · 11 October 2003, 22:22

i had a 4.8 bombard with a 75hp and it needed it even though the boat was rated for a 60 hp max. i now have a 5.5 with a 100 and with lots of weight i wished i had a little more power.

Thepooster2002 · 11 October 2003, 22:35

Interesting to see on Honda's web site that they recomend a 50hp for a 5.5m Rib, maybe they mean 2of em

thewavehumper · 12 October 2003, 00:07

3

Daniel · 12 October 2003, 16:25

You can never have enough power (until the transom starts falling off) and i would be looking at 100hp + for a 5-5.5mtr boat.

Am selling / have just sold my 18' BWM which was a nice match to the Yam 130 she had.

Why not think about buying another Honda (keep the 1st) 45 and having a nice twin engine set-up? That would be a superb peice of kit???

Richard B · 12 October 2003, 16:47

He, he... you don't half like your power, Daniel!

About 75hp for a 5m, 90hp for 5.5 should be a good yardstick for reasonable performance - anything more will give you lots of oomph! Just beware that if you go for more oomph, your hull needs to be able to cope with the extra power as over-powered craft can get very difficult to control. And insurance can be difficult to get for over-powered craft.

simmons0 · 12 October 2003, 16:50

no offense daniel but u really havent a clue what your on about.
You can definatly have to much power, consider firstly hull speed, secondly weight. One of my friends has a BWM 18 with a 150hp johnson. 150hp being the absolute max as said by the maker. This is massivly overpowered. It doesnt ride well, it doesnt turn and i dont think he has ever given it full power in his life. Added to that fuel bill of around £600 for a weeks ribbing. Please sound less liek my 11 year old son, overpowered boats are awful.

Richard B · 12 October 2003, 17:01

Steady on Simmons0... I think Daniel's sea miles speak for themselves - but it's interesting to hear about the Johnson 150 powered BWM - sounds like Daniel's got "Grayswish" on the true limit of power for that hull. I guess that the 150hp Johnson is a V6 VRO and I think that Daniel's is a Yam V4 which would make a big difference to the weight and therefore the handling of two similar hulls.

Daniel · 12 October 2003, 17:09

I stand by my comment, but shall reword it. There is no such thing as too much power within the limits of the boat (which should be the same as the manufacturers reccomendations) and in sensiable hands.

I deliberatly underengine all the boats for...1) the Sailing Club and the 2) the Sea Scouts because group 1) mostly have no idea what they are doing and group 2)... they only understand stop or go(=full power).

I've owned quite a few boats and, infact, teach lots of peope all about boats every year, so i think i know what i am on about.

A big engine can be as, or even more efficient than a smaller one - for example my last boat would trundle along all day at 25knts, 4000rpm, 30ltrs per hour. My friends boat with a 60hp is flat out to keep up and he eats fuel at about the same rate. The difference is i can make 45knts if i want to (and it's flat enough) and i've bags of power for towing, driving in the rough etc.

With regards to your friends boat i think he should review the set-up. Unless the 150 is substantialy heavier than the (167Kg) Yam 130 then it's either loaded badly, mounted too high / low, not enough offset, or even (as in a previous boat i had) the steering system needs replacing.

I don't know everything, i'm just voicing my opinion and trying to be helpful. I've no more idea of your experience than you have of mine.

I'd regret buying a 5m boat and putting a 45 on it.

Daniel · 12 October 2003, 17:14

Quote:

Originally posted by Richard B
the 150hp Johnson is a V6 VRO

Which would make a big difference. The manufacturer would not only reccomend a max HP but weight as well. About 180Kg in the case of the DS18 i think becasue i looked at putting an Optimax 150 on it a year or so ago and decided it would be over the manufacturers max weight!

simmons0 · 12 October 2003, 23:21

Hey i apologise to you Daniel.

I think your second explanation was better though. As for my friends boat i think the prop will have alot to do with the problems. Maybe he should experiment with different props.

Definatly though a 45 on a 5m boat would be criminal especially if you want to carry around divers. Im currently selling a Valiant v-490. Matched up to a yamaha 60 it is perfect however being a valiant (PVC tubes) it doesnt weigh much.
On somthing like a ribcraft you would want more power.

I always think that 3/4 of the manufacturers maximum is about right unless you are going to be lugging around lots of divers and their equipment.

Thepooster2002 · 13 October 2003, 20:45

Have a look at this site http://www.hondaoutboard.co.uk/ then go to Techtalk/Choosing right HP, look at the BF50, they recomend it for a 5.5m Rib, are they talking bllx ??

Richard B · 13 October 2003, 21:46

In a word... Yes! They seem to be recommending the absolute minimum. They only seem to have got it right on the two biggest engines. Maybe it's a marketing ploy to encourage people to power up after their first season.

simmons0 · 13 October 2003, 21:52

If you put a 50 hp engine on a delta 5.5 it wouldnt move, you may get away with it on a lighter boat though