humber 5.5m assult cruising speeds

seafreak · 10 November 2008, 16:42

i have humber 5.5m assult with opti 115hp, with 5 on board and 75lts of fuel we seem to race up to 37knts{in resonable conditions} but then we start to chine walk quite alarmingly i back off throttle and things calm down , 33knts is a good easy cruising speed, am i asking too much to want to cruise faster, or is it my inexperience?

Jono Garton · 10 November 2008, 17:36

Quote:

Originally Posted by seafreak

am i asking too much

Yes , we aim to cruise at 25 knots

It's well over powered for an Assault, 75hp Would be ample.

Is it Dave Grittifths old boat?

Jono

chewy · 10 November 2008, 18:30

The 5.5 Assault is only rated to 90hp and 175kg, the dry weight of your Opti is 170kg so its boarder line.
Not sure how much this is contributing to your problems but the fact its over powered won't help things.

Phill

BruceB · 10 November 2008, 19:07

I wouldn't want to hit any waves or bumps in an assault at 37knts. Your feet would come up through your body.........
I thought hitting small waves at 25knts was bad enough, one of the reasons I got rid of mine.
You must be well 'ard

Jono Garton · 10 November 2008, 19:18

80% of our customer that come to sea trial Assaults buy Destroyers, the other 20% want to keep them in a garage or only have a mini metro to launch with. I still like the 4.7m & 5m Assualt.

Jono

seafreak · 10 November 2008, 19:33

forsure theres nothing well ard about me, just want to make the most of what i got. i re engined this humber, the boat is year 2000 and the sales lit that came from humber states 174kg max and 115hp so i just went for the max i could, although if you look at the latest sales blurb , humber seem to have calmed the assault down a bit to 90hp. anyway this is what ive got until i can afford to put this engine on something else, so, should i be happy to cruise at 33kts or does anyone have any ideas?

Jono Garton · 10 November 2008, 19:40

You should be happy with 33knots, I'm happy at cruising at 30 knots in my 6.3 Ocean Pro, just be carefull at full revs it a quick rig

Jono

chewy · 10 November 2008, 19:43

Whats the CE plate say your Assault is rated to?

seafreak · 10 November 2008, 20:11

i,ll check for the ce plate when i next get down to hamble point, i,m not sure where to find it though. thanks for all your info,i just wasnt sure if i was geting the best out of it. so guys, if i want to cruise more quickly with my opti, and i love the humber, which one should i go for next time?

chewy · 10 November 2008, 20:19

If your getting to your max speed really quick it could be under propped, are you hitting max rpm too?
The CE will be mounted on the inside of the transom, its usually near the Orca plate that Humbers have fitted.

If your happy with Humber a Destroyer or Ocean Pro might be the next move?

seafreak · 10 November 2008, 20:29

thanks, i,ll have a close look. as far as revs go it was doing 4800 at 37knts i think it had more to give.

chewy · 10 November 2008, 20:31

Sounds like you had another 1000 revs to go!

seafreak · 10 November 2008, 20:43

so i guess i,m not going to wear the engine out then. will a destroyer/ ocean pro give me more speed and a softer ride? also , ok sorry for all the questions. what will one give me over the other in the same sizes?

BruceB · 10 November 2008, 20:44

It sounds if the hull will do well over 40knts then?
Good luck, you will need it if you hit any waves at that speed in an Assault Hull

I sold mine last year because I couldn't handle the ride at half that speed, any distance and we were sore for days.......

And the number of times we stuffed or slammed into quite small waves HARD is beyond counting.
I would dump it and put your engine on something much deeper V and softer riding as soon as you can, its a pretty crap hull all round.........

You will most probably drop some speed in something like a destroyer as it will be heavier for the same length and consequently have a larger wetted area and beam. But the ride will be very much drier and softer and the seakeeping immeasurably superior!
Either that or try and get hold of a Attaque, this would fly with a 115 as long as the boat rating would take it. Much the same size, beam and weight as an Assault but better hull form.

Chris · 10 November 2008, 20:46

A freind of mine has what I think is an assault its got 90HP on the back and goes like a rocket however chine walked badly once you started to trim out when at WOT. We found fitting a pair of dolefins to the Cav Plate made a huge difference and now it is much more controlable at speed.

seafreak · 10 November 2008, 20:50

ok chris what is wot?

Chris · 10 November 2008, 20:51

Quote:

Originally Posted by seafreak

ok chris what is wot?

Wide Open Throttle

or in Mollers world (so I hear) "Forwards"

seafreak · 10 November 2008, 20:59

thankyou everyone for all your input to my "probably" inexperienced questions, it looks like i need a more capable hull for what i want to do, but as always i need to justify things to ;well you know who,so i will be careful with my assult for next season, try to learn its foibles, and get a better hull next time. ps , if you see us in the solent , just smile and wave as you go past.cheers

chewy · 10 November 2008, 21:04

Quote:

Originally Posted by seafreak

thankyou everyone for all your input to my "probably" inexperienced questions, it looks like i need a more capable hull for what i want to do, but as always i need to justify things to ;well you know who,so i will be careful with my assult for next season, try to learn its foibles, and get a better hull next time. ps , if you see us in the solent , just smile and wave as you go past.cheers

Wave as you go past, I doubt it if your doing 37kts and have 1000rpm left in reserve!

The Assault ain't a great hull but you'll learn from your mistakes using that boat and get a shock how much more comfy bigger boats are.

seafreak · 10 November 2008, 21:08

cheers all, jonathan.