RIB not planing

Fishman1969 · 31 May 2021, 09:02

Hello,
I am fairly new to RIB motoring, but I have friends who have tried advising to no joy.
I have a Valiant V520 with a Honda 75HP 4 stroke outboard. When I give a bit of power the bow comes up and does not go back down again. I tried trimming engine but no joy. Any advice appreciated please as not got the throttle over half way yet as worried about inclining even more.

Pikey Dave · 31 May 2021, 10:42

Quote:

Originally Posted by Fishman1969

Hello,

I am fairly new to RIB motoring, but I have friends who have tried advising to no joy.

I have a Valiant V520 with a Honda 75HP 4 stroke outboard. When I give a bit of power the bow comes up and does not go back down again. I tried trimming engine but no joy. Any advice appreciated please as not got the throttle over half way yet as worried about inclining even more.

Have you actually got over the “hump” & onto the plane?

GuyC · 31 May 2021, 10:54

The bow coming up is normal. It's part of the transition from displacement speed to planing and is your boat climbing over your bow wave.

If you get to full throttle and you are still in the same attitude, then you do have an issue.

Welcome to the forum. That is a new and slightly worrying question.

Fishman1969 · 31 May 2021, 11:11

Quote:

Originally Posted by Pikey Dave

Have you actually got over the “hump” & onto the plane?

I was half throttle for 15 minutes and bow stayed up. Am I being a novice boater and doing something wrong??

TmMorris · 31 May 2021, 11:12

Did you not keep pushing the throttle to get the boat over the bow wave and o to the plane? Once on the plane you can throttle back.

treerat · 31 May 2021, 12:02

Stop being so gentle, got to get up and going proper.

Limecc · 31 May 2021, 12:58

If you want it to come up nice and gradual, fit a Doel Fin. Most on here don't like them but works for us.

Fishman1969 · 31 May 2021, 13:08

Quote:

Originally Posted by TmMorris

Did you not keep pushing the throttle to get the boat over the bow wave and o to the plane? Once on the plane you can throttle back.

So when the bow lifts keep pushing forward and it will level out? 👍

Iankristy · 31 May 2021, 13:34

Bear in mind also that the bow should be up when your planing, it will be harder to see over the bow. It’s only the rear third or so of your boat that’s still in the water. Simple planing procedure is:
- out board fully trimmed in
- give it some throttle(prob bit more than half)
- as stated you’ll need to get over hump
-trim up and watch the spray up the side of your boat, it will work it’s way back until only back third(ish) of boat is throwing up spray.
- trim up till prop starts slipping and you’ll here the revs rise suddenly then trim back in until it bites. Your on the plane. You can decrease speed and stay on the plane but you’ll need a minimum speed to stay on it( about 15knts ish on mine) You’ll soon get used to your boat and won’t have to do that bit
Try this on nice flat water, don’t be afraid to give it beans. Bow will not rise until it flips [emoji23]

Most important thing to bear in mind is when turning you need to trim in and get the keel in the water. If not boat can start slipping sideways and when keel catches water you will ‘hook’ the boat. This will exert huge lateral forces on your boat and you’ll probably get wet. Keel in for cornering (mostly) out for planing

Pikey Dave · 31 May 2021, 13:54

Maybe a good idea for the OP to find someone with some RIB experience to show him the ropes. Or do a RYA PB course.

Fishman1969 · 31 May 2021, 14:54

Thank you. I will be giving it a blast tonight so will let you know later or tomorrow how it goes ��

jeffstevens763@g · 31 May 2021, 18:53

Give it some welly work from there

pagick · 31 May 2021, 19:34

You have lots of good advice so far. And here is mine.
I’ve owned 8 different boats in my life. My process to get on plane is always to trim your OB in all the way. Give full throttle and as I reach the speed I want I pull back the throttle. If you’re final speed you want falls into the speed your boat just starts to plane then adjust your desired speed to be a bit faster so you don’t have to fight your boat falling off plane.
I have a couple kids who want to wakeboard at the transition to plane speed and it was such a battle I bought a PerfectPass speed controller. It worked great but cost a lot.
P.S.having all available meat move forward helps a lot compared to that same weight sitting behind you. HUGE DIFFERENCE!

Dkovac · 31 May 2021, 23:40

Is it possible your engine isn't running on all cylinders? This would prevent it from having the power to get over the hump and onto the plane. You can check relatively easily. Search YouTube on how to check you're getting engine spark.

Limecc · 01 June 2021, 06:07

Quote:

Originally Posted by Dkovac

Is it possible your engine isn't running on all cylinders? This would prevent it from having the power to get over the hump and onto the plane. You can check relatively easily. Search YouTube on how to check you're getting engine spark.

Please re-read original post

Johno99 · 01 June 2021, 06:42

I have a Valiant 4.5 and had the same problem when I bought it. I simply got around this by putting ballast blocks in the anchor locker, but first get people to sit fwd in the boat and see if that helps.

Dkovac · 01 June 2021, 06:50

Quote:

Originally Posted by Limecc

Please re-read original post

I just didn't think modifying a boat to get it to plane was the answer. It's either driver error or the boat needs repair of some kind. If it's driver error then he really needs to do a driving course because getting a boat to plane is one of the easier skills required to drive a boat. If it's not driver error then a lack of power is a problem I have had getting a boat to plane in the past. Not saying it's definitely the problem for him given we can't see what's happening but it's possible. A 75hp engine at half throttle should get pretty close to getting it out of the hole I would have thought.