Reply
 
Thread Tools Search this Thread
 
Old 07 December 2005, 16:14   #1
Member
 
Country: Ireland
Town: Dublin
Length: 5m +
Join Date: Dec 2005
Posts: 2
Too much power?

I'm buying a Humber 5.5m Ocean Pro and I'm waivering over which engine I should get. My previous boat was a 5.4m Tornado with a Yamaha 90 2-stroke. She had alot of difficulty getting on the plane with 6 divers and a coxswain so I'm keen to avoid a similar problem this time. Just to make things interesting, I'm also fairly tightly constrained by weight because I'll be towing with a normal family car, so the lighter the better and 4-strokes are right-out. At the moment I've pretty much made up my mind on a 115HP Evinrude E-tec, which is 50Kg heavier than the Yamaha 90 but I think necessary none the less. Does anyone have a similar boat, what engine did you go for? Is the 115HP overkill? Or does anyone have any recommendations either way?
__________________
Will F is offline   Reply With Quote
Old 07 December 2005, 16:22   #2
RIBnet supporter
 
bogib's Avatar
 
Country: Iceland
Town: Reykjavik
Boat name: Cheesee
Make: Seaquel 600 XS
Length: 6m +
Engine: Mercury 275 Verado
Join Date: Aug 2003
Posts: 1,959
Send a message via Skype™ to bogib
What about Mercury / Mariner 115 Optimax, weight about 170 kgs

Bogi
__________________
RIBs and ribbing is my life
www.sjosport.is
bogib is offline   Reply With Quote
Old 07 December 2005, 16:25   #3
Member
 
Hugh Jardon's Avatar
 
Country: UK - England
Town: Reading, Hants
Boat name: Juicy
Make: Sealine F43
Length: 10m +
Engine: 2 x 370hp
MMSI: TBC
Join Date: Sep 2005
Posts: 2,884
ask the dealer if they can supply a 2005 engine for you at a discounted price, ie for merc or mariner that is....

if the boat is rated for 115 then you have no problems, always better to go bigger than smaller if the car towing situation will allow

if the boat can take a bigger engine and the bigger engine is the same weight as the 115 then go bigger

Quote:
Originally Posted by Will F
I'm buying a Humber 5.5m Ocean Pro and I'm waivering over which engine I should get. My previous boat was a 5.4m Tornado with a Yamaha 90 2-stroke. She had alot of difficulty getting on the plane with 6 divers and a coxswain so I'm keen to avoid a similar problem this time. Just to make things interesting, I'm also fairly tightly constrained by weight because I'll be towing with a normal family car, so the lighter the better and 4-strokes are right-out. At the moment I've pretty much made up my mind on a 115HP Evinrude E-tec, which is 50Kg heavier than the Yamaha 90 but I think necessary none the less. Does anyone have a similar boat, what engine did you go for? Is the 115HP overkill? Or does anyone have any recommendations either way?
__________________
Hugh Jardon is offline   Reply With Quote
Old 07 December 2005, 17:46   #4
Member
 
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,653
If I were you, I'd find what the hull is rated for, and make your decision on which motor based on that.

As a fellow diver, I am well aware of the amount of weight a boat loaded with gear and divers (and, on the trip back, water) has to deal with; go max power and you won't have to second-guess your purchase.

Given that you will be adding a ton (literally) of weight in the passenger area, a few more pounds in back is not going to matter all that much, I think.

jky
__________________
jyasaki is offline   Reply With Quote
Old 07 December 2005, 21:56   #5
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
Some folk on ribnet rate the Suzi 140. That would give you the extra oomph for carrying your gear.
__________________
JW.
jwalker is offline   Reply With Quote
Old 07 December 2005, 22:14   #6
Member
 
Country: UK - England
Town: Newquay, Cornwall.
Boat name: None :(
Make: None :(
Length: 5m +
Engine: None :(
MMSI: None :(
Join Date: Jun 2005
Posts: 1,280
Quote:
Originally Posted by jwalker
Some folk on ribnet rate the Suzi 140. That would give you the extra oomph for carrying your gear.
I have one - on my ribcraft 5.85 - love it.

You also have to remember its lighter than ther suzuki 90hp
roycruse is offline   Reply With Quote
Old 08 December 2005, 09:12   #7
Member
 
Country: UK - England
Town: Portsmouth
Make: Tornado
Length: 6m +
Engine: Yamaha HPDI 200
Join Date: Jan 2003
Posts: 323
Send a message via MSN to thorper
For getting the rib on the plane loaded with divers, its the torque / pickup you want rather than raw power at the top end. You defnintely want a 2 stroke for pushing load around at that size.

The prop you pick for carrying load is important as well - worth discussing with the dealer when you buy the boat.

Our club dive rib (6m) has an Optimax 115, which pushes 6 divers + a cox up on the plane without too much bother, and it is a good engine too.

Ricky
__________________
thorper is offline   Reply With Quote
Old 08 December 2005, 18:38   #8
Member
 
Country: USA
Town: San Francisco
Boat name: Vitamin Sea
Make: Zodiac Pro Open 650
Length: 6m +
Engine: Yamaha 115
Join Date: Feb 2005
Posts: 5
You can also change the prop to one that lets you get to a plane faster. That might save you a lot of money.
__________________
Surferdude is offline   Reply With Quote
Old 08 December 2005, 20:07   #9
Member
 
Hugh Jardon's Avatar
 
Country: UK - England
Town: Reading, Hants
Boat name: Juicy
Make: Sealine F43
Length: 10m +
Engine: 2 x 370hp
MMSI: TBC
Join Date: Sep 2005
Posts: 2,884
and try doel fins on the prop, they work wonders in certain situations
__________________
Hugh Jardon is offline   Reply With Quote
Old 08 December 2005, 20:36   #10
Member
 
Country: UK - England
Town: Hamble
Length: 9m +
Join Date: Dec 2002
Posts: 2,317
Quote:
Originally Posted by Hugh Jardon
and try doel fins on the prop, they work wonders in certain situations
Can't imagine what situation that would be, might be worth trying them on the cav plate though!
__________________
It is better to remain silent and be thought a fool, than to speak and remove all doubt!
Dirk Diggler is offline   Reply With Quote
Old 08 December 2005, 20:50   #11
Member
 
Hugh Jardon's Avatar
 
Country: UK - England
Town: Reading, Hants
Boat name: Juicy
Make: Sealine F43
Length: 10m +
Engine: 2 x 370hp
MMSI: TBC
Join Date: Sep 2005
Posts: 2,884
now that would be a sight to see

yes cavitation plate it is, oooops what a birk!! playing with my new laptop here so brain not totally engaged
Quote:
Originally Posted by Dirk Diggler
Can't imagine what situation that would be, might be worth trying them on the cav plate though!
__________________
Hugh Jardon is offline   Reply With Quote
Old 09 December 2005, 10:08   #12
Member
 
Country: Norway
Join Date: Oct 2003
Posts: 155
We used to have a 5.5 Bombard rated for 90 hp. We had 115 Johnson 2-stroke. It did 42 knots on GPS when two persons on board. This was the speed we wanted for cruisingspeed. We always wanted more hp and looked at 150hp so that we could cruise at 40+ knots.
Ask the builder if the transom can hold the extra hp, so you don`t break anything. When bying a new boat, you can specify the transom yourself.
__________________
Fjordrafting is offline   Reply With Quote
Old 09 December 2005, 12:02   #13
Member
 
Simon B's Avatar
 
Country: UK - England
Town: Leicester
Boat name: Vixen
Make: Ribcraft
Length: 6m +
Engine: Suzuki OB 175
MMSI: 235071839
Join Date: Jun 2004
Posts: 1,624
Will F,

Our club currently runs a Delta 5.5 with a Yam 100 hp 4 stroke. We wanted the F115A but didnt have the money. Its a heavy motor and we pay for this due to the whole thing being stern heavy. We also used the the Yam stock prop which was well out in terms of pitch for the speed we needed and ability to plane with 6 divers and 2 crew.

The biggest difference to date has been going down in pitch and using a 4 blade prop. We particularly noticed this when you are just off the plane and climbing the front of a wave, previously it was like slowly driving into treacle.

We will be fitting lifting foils but I'd like to wait until some new stock of "Tigershark" Vortex groove foils arrive and try them.
__________________
New boat is here, very happy!
Simon
www.luec.org
Simon B 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




All times are GMT. The time now is 01:03.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.