What speed

[BigE]

I was out enjoying the boat yesterday and all was fine but I wondered if it was all working as well as it should. A bit of a vague question but, here goes:

What speed (MPH or Knots) would you expect a Bombard Explorer with a 50HP Honda engine on the back and 1 adult + two light weight children to achieve?

The sea conditions were a bit choppy if that makes any difference.

Any guesses?

[jeffstevens763@g]

What were you getting or had no way of knowing there's a phone app that will tell you I get 22 knots with a 25
Is the explorer a rib?

[BigE]

According to my phones GPS it said I was achieving about 22mph which seemed slow. It's a 5.5m RIB with a Honda 50HP 4 stroke.

I just don't know if it should be able to go faster or not.

Do you mean you get 22knots with a 25HP engine? What size boat?

[gpsguru]

I would think 22mph (19knts) is about right ................. 50hp is pretty small for a 5.5m RIB ........... I would be looking at an minimum of 75 - 90 hp .

My 4.2m RIB has 40hp which gives me a shade over 30knts(35mph) flat out.

[BigE]

That's good to know, I was aware 50HP was a bit small. We're going to keep it for this year and then next spring we'll upgrade to something a bit more beefy.

I'm going to get some new carbs fitted as it's running a bit flat so that may help, compression is good on all cylinders and it's been given a good service.

[jeffstevens763@g]

look on the suzuki site they have some engine performances with different boats not the same as you i know but you might get some info to compare

[BigE]

Thanks for that, I'll take a look.

As the weather improved this afternoon we went for a quick blast. Lovely being able to do that on a whim. About 15 minutes from door to being on the water.

The sea today is a lot calmer and the speed nudged up to 24mph off Hurst Spit.

[jeffstevens763@g]

Originally Posted by BigE

Thanks for that, I'll take a look.

As the weather improved this afternoon we went for a quick blast. Lovely being able to do that on a whim. About 15 minutes from door to being on the water.

The sea today is a lot calmer and the speed nudged up to 24mph off Hurst Spit.

What revs are you at anywhere near the maximum range and have you played with trim both can hold her back

[BigE]

No rev counter unfortunately, the throttle is on full. I've adapted the trim and it's as fast as I could get.

[Ceejay]

I used to get 27 knots with a 50 hp Suzuki on a Valiant 4.9DR. That was flat out with one up,and a clean hull with hard tubes. I would guess that your prop is perhaps on the course side and you're not pulling max revs, which in turn is not good for the engine. What pitch is your prop, think mine was 13 inches?

[BigE]

My prop is in a sorry state, one blade is bent, one has a small chunk taken out of it and the other is nicked. I was thinking of just fitting a new one.

The current prop is 11.1 inch diameter with a 15" pitch

As I said, a new prop is probably in order to go with the new carbs being fitted this week. I'm told the engine compression is great so once the carbs are fitted I'll move on to the prop.

It doesn't help that there seems to be a lot of water build up in the hull so even with pumping it all out I've probably got the weight of a small child in it just sloshing around.

[BigE]

Just added to my post above the current prop is 11.1 inch diameter with a 15" pitch, 3 blade.

[jeffstevens763@g]

to be brutal you're peeing in the wind with all the issues you have prop, water, carbs, revs,
you could get the revs sorted by buying a tiny tach equivalent for around twenty quid you need that to select a prop ok you're props damaged but its a base to start at if you dont want to spend at this present time. you're sorting the carbs so one step in the right direction, you need to get rid of the water issue is your drain plug leaking? thats a quick fix if it is carrying extra weight sloshing around will dramatically reduce performance.
have a look at SSI MARINE OUTBOARDS for a new prop i got one for £62 for my 25hp