Reply
 
Thread Tools Search this Thread
 
Old 27 August 2019, 09:18   #1
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Rib Nose up???

Can anyone help. I have a 4.2m rib with a mercury 60 four stroke. When in harbour at 6knts it sits nice and flat. Above this the nose sticks up ridiculously Like it’s trying to push under itself until it planes. Can anyone offer advice regarding engine position/trim/anything to improve this. If I try to pull a skier out the whole (heavy 95kg sods like me) the boat pitches nose up and struggles to get on the plane and acts more like a damn!

Engine height? Up or down? Would this help? All technical/practical advice appreciated.
__________________
cheeseboat is offline   Reply With Quote
Old 27 August 2019, 09:26   #2
Member
 
Iankristy's Avatar
 
Country: UK - Scotland
Town: Scotland
Boat name: Clyde adventurer
Make: Humber
Length: 8m +
Engine: Twin Merc 150 4str
Join Date: May 2015
Posts: 472
Hydraulic or fixed trim?
__________________
Iankristy is offline   Reply With Quote
Old 27 August 2019, 09:37   #3
Member
 
Country: New Zealand
Town: Whakatane
Boat name: Jojosrib
Make: Brig
Length: 6m +
Engine: Yamaha f 130
Join Date: May 2016
Posts: 49
Quote:
Originally Posted by cheeseboat View Post
Can anyone help. I have a 4.2m rib with a mercury 60 four stroke. When in harbour at 6knts it sits nice and flat. Above this the nose sticks up ridiculously Like it’s trying to push under itself until it planes. Can anyone offer advice regarding engine position/trim/anything to improve this. If I try to pull a skier out the whole (heavy 95kg sods like me) the boat pitches nose up and struggles to get on the plane and acts more like a damn!

Engine height? Up or down? Would this help? All technical/practical advice appreciated.
I assume the engine isn’t too heavy......and the weight on the boat is at least central or preferably forward.....and the motor is trimmed in....if those basics are ok you may need to look at fitting some wedges for the engine mounts.... it’s also asking a lot for a 4.2 m boat to be comfortable in pulling out a95 kg skier..
__________________
Jojosrib is offline   Reply With Quote
Old 27 August 2019, 09:45   #4
Member
 
Last Tango's Avatar
 
Country: UK - Scotland
Town: Denny
Boat name: Highland Bluewater
Length: 6m +
Join Date: Mar 2013
Posts: 1,647
Right leg length.....L, XL..? Prop set too deep ?.
__________________
Last Tango is offline   Reply With Quote
Old 27 August 2019, 10:02   #5
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by Iankristy View Post
Hydraulic or fixed trim?


Thanks for responding

It’s hydraulically trimmed. Trimmed full down.
__________________
cheeseboat is offline   Reply With Quote
Old 27 August 2019, 10:04   #6
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by Jojosrib View Post
I assume the engine isn’t too heavy......and the weight on the boat is at least central or preferably forward.....and the motor is trimmed in....if those basics are ok you may need to look at fitting some wedges for the engine mounts.... it’s also asking a lot for a 4.2 m boat to be comfortable in pulling out a95 kg skier..


I think yes to those basics but need to check properly.

So would wedges to push the top of the engine back be worth a try?
I never need to trim up when planing.
__________________
cheeseboat is offline   Reply With Quote
Old 27 August 2019, 10:05   #7
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by cheeseboat View Post
I think yes to those basics but need to check properly.

So would wedges to push the top of the engine back be worth a try?
I never need to trim up when planing.


And yes, I appreciate it’s asking a lot! I would loose weight but drinking and eating too much is for more inviting 🤣🤣🤣
__________________
cheeseboat is offline   Reply With Quote
Old 27 August 2019, 10:07   #8
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by Last Tango View Post
Right leg length.....L, XL..? Prop set too deep ?.


The “ventilation” (I thinks that’s what it’s called) plate (the bottom flat fin) is roughly level wth the bottom of the transom.
__________________
cheeseboat is offline   Reply With Quote
Old 27 August 2019, 10:36   #9
Member
 
lakelandterrier's Avatar
 
Country: UK - England
Town: Gloucester
Boat name: Lunasea
Make: Ribcraft
Length: 5m +
Engine: Suzi 140
MMSI: 232005050
Join Date: Sep 2007
Posts: 1,978
The centre of gravity may be too far back I had same problem with my 4m Avon.with a 4stroke 40HP
On plane engine should be trimmed up c.halfway

I'd move what weight I can -batttery, fuel, etc. forward & see what effect that has.

Have you considered fitting Doelfins? - I found they made a huge difference.

Think about some ballast in bow as a further option

LT
__________________
Member of the Macmillan Round the Isle of Wight Club
lakelandterrier is offline   Reply With Quote
Old 27 August 2019, 10:59   #10
Member
 
Country: UK - England
Town: Cheltenham
Make: Marex
Length: 9m +
Join Date: Oct 2011
Posts: 344
RIBase
very low powered engine to pull a 95Kg skier but it sounds like you have other issues at play to sort out first.
__________________
You Can't cross an Ocean unless you have lost site of shore.
charliee is offline   Reply With Quote
Old 27 August 2019, 11:49   #11
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by lakelandterrier View Post
The centre of gravity may be too far back I had same problem with my 4m Avon.with a 4stroke 40HP
On plane engine should be trimmed up c.halfway

I'd move what weight I can -batttery, fuel, etc. forward & see what effect that has.

Have you considered fitting Doelfins? - I found they made a huge difference.

Think about some ballast in bow as a further option

LT


Thanks LT, really helpful. I’ll try all these tips.
__________________
cheeseboat is offline   Reply With Quote
Old 28 August 2019, 09:14   #12
Member
 
Country: Netherlands
Boat name: Tempo
Make: Scorpion 8.1 Mk1
Length: 8m +
Engine: Honda BF225
Join Date: Jun 2013
Posts: 58
I have the same problem with my little 330 rib, 15 hp. All I have to do is send the passenger forward and away it goes
So it's probably a weight problem.
__________________
otilly is offline   Reply With Quote
Old 28 August 2019, 09:28   #13
Member
 
Country: UK - England
Town: Retford
Boat name: Spy-sea-one
Make: Excel 435
Length: 4m +
Engine: Suzuki Outboard/25/4
Join Date: Oct 2011
Posts: 7,443
RIBase
not got water in the hull if thats the type of design, it should have a drain plug at the stern
__________________
jeffstevens763@g is offline   Reply With Quote
Old 28 August 2019, 14:16   #14
Member
 
Country: USA
Make: AB
Length: 3m +
Engine: outboard, 40hp
Join Date: Feb 2016
Posts: 97
I would recommend "automatic" trim tabs, whatever brand you prefer. I have nauticus smarttabs on my rib and without them I can't get on plane with only me. It's too stern heavy.
They are spring loaded so they self retract when you get on plane. They have a chart on their website to fit the right spring strength.
You can also get a kit to manually retract them so they are not in the way for trailering. Sometimes I forget to put them down coming off the trailer and I instantly know whats wrong.
__________________
babbot1 is offline   Reply With Quote
Old 28 August 2019, 19:37   #15
Member
 
Country: UK - England
Town: Stratford upon Avon
Length: 4m +
Join Date: Apr 2018
Posts: 42
I have a 4.2m zodiac pro with Yamaha 40hp 2 stroke. I weigh 85.3kg and the rib pulls me out with ease and that includes 3 adults on board. So not convinced there is a power issue. Like your rib when in harbour it rides very nose high and nose high before going on plane. In my case it’s definitely a weight distribution problem. Mine is back heavy and I bet yours with a 60hp 4 stroke will be too. Move bodies (weight) up front and this significantly reduces the nose up for me. Mine is a jockey seat with anchor spare fuel all up front. 40litres fuel and battery under seat. Still rear Heavy. Apart from adding permanent weight up front (or making people go up front (if they are on boar) until on the plane) the only other solutions/improvements I can see might be the use of the dolphin fins or the auto trim tabs mentioned by others and I haven’t tried either. I’m tempted tho. But your not alone. Good luck.
Bremar
__________________
Bremar is offline   Reply With Quote
Old 28 August 2019, 23:09   #16
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,622
Quote:
Originally Posted by jeffstevens763@g View Post
not got water in the hull if thats the type of design, it should have a drain plug at the stern
Definitely worth checking
__________________
Poly is offline   Reply With Quote
Old 29 August 2019, 07:08   #17
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by Bremar View Post
I have a 4.2m zodiac pro with Yamaha 40hp 2 stroke. I weigh 85.3kg and the rib pulls me out with ease and that includes 3 adults on board. So not convinced there is a power issue. Like your rib when in harbour it rides very nose high and nose high before going on plane. In my case it’s definitely a weight distribution problem. Mine is back heavy and I bet yours with a 60hp 4 stroke will be too. Move bodies (weight) up front and this significantly reduces the nose up for me. Mine is a jockey seat with anchor spare fuel all up front. 40litres fuel and battery under seat. Still rear Heavy. Apart from adding permanent weight up front (or making people go up front (if they are on boar) until on the plane) the only other solutions/improvements I can see might be the use of the dolphin fins or the auto trim tabs mentioned by others and I haven’t tried either. I’m tempted tho. But your not alone. Good luck.
Bremar


Thanks for replying. I understand and agree. The only thing on your side is the instant power of the 2 stroke. I’m going to try some weight shifting and also the wedges to see if I can use the engine to improve the stern lift. This should also give me some trim when I’m planing as I currently don’t have any need to. If that doesn’t work I’ll try the fins or tabs. I’ll report back so all who have offered help can read the results if your interested.
Thanks again
Cheeseboat.
__________________
cheeseboat is offline   Reply With Quote
Old 29 August 2019, 07:09   #18
Member
 
Country: UK - England
Town: Little Easton
Boat name: Cheese
Make: Excel Virago
Length: 4m +
Engine: Outboard Mercury 60H
Join Date: Jun 2018
Posts: 22
Quote:
Originally Posted by babbot1 View Post
I would recommend "automatic" trim tabs, whatever brand you prefer. I have nauticus smarttabs on my rib and without them I can't get on plane with only me. It's too stern heavy.
They are spring loaded so they self retract when you get on plane. They have a chart on their website to fit the right spring strength.
You can also get a kit to manually retract them so they are not in the way for trailering. Sometimes I forget to put them down coming off the trailer and I instantly know whats wrong.


Thanks. I’ll try these if the wedges don’t do it.
__________________
cheeseboat is offline   Reply With Quote
Old 30 August 2019, 08:46   #19
Member
 
Country: UK - Scotland
Town: Aberdeen
Boat name: Moby 2
Make: Northcraft
Length: 5m +
Engine: honda BF100
MMSI: 232015658
Join Date: May 2014
Posts: 21
Try a 4 blade prop that’s helped me. Now it just hops up onto the plane
__________________
hesko is offline   Reply With Quote
Old 31 August 2019, 07:49   #20
Member
 
Country: UK - England
Town: penzance
Boat name: not named
Make: ski boat
Length: 5m +
Engine: 150 HPDI
Join Date: Sep 2013
Posts: 224
Quote:
Originally Posted by hesko View Post
Try a 4 blade prop that’s helped me. Now it just hops up onto the plane
Same pitch?
__________________
simonl is offline   Reply With Quote
Reply

Tags
rib

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 16:47.


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