Triming problem

Jason calleja · 15 August 2014, 15:49

Hi all I would like if someone ever experienced this kind of problem.
I have a 17.5ft RIB and it have a Honda BF90 Vtec I am having a problem with trim when I pick up speed and revs and try to trim the motor for a little bitt the motor is like to get out of water and loose speed instead of gaining speed It is consuming a little bitt of fuel too. I don't have any problem to plane as if I get the throttle to WOT i am on plane and it dose not get more than 4sec to plane. I am thinking that I may have a small prop the prop is 13"x19pitch I cannot try to check if it have the right pitch by rev as I told you as soon as I try it get out of water rev a lot and loos speed. Btw when ever I tried It was loaded with 5 persons. what do you think?. thanks

matt h · 15 August 2014, 16:18

Motor set too high?
Prop sounds about right
Cav plate normally should be 1/2 above bottom of hull when straight

Jason calleja · 15 August 2014, 16:32

I will check for the hight of the cavation plate.
The propeller selector on honda web side is indicating
that prop should be 21to23 pitc

Peter_C · 15 August 2014, 16:56

Take two horizontal pictures, with one from astern and one from the side, then post them up. Be as close to level with the boat bottom as you can.

Sure sounds to me like the engine is too high.

Jason calleja · 15 August 2014, 17:06

Tomorow morning I will take pictures. Thanks

Jason calleja · 16 August 2014, 12:09

I have checked the cav plate and it is in proper height. I don't know how to attach the picture. so I think that I will have to try a higher pitc prop. if you can tell me how I will upload pict. thanks

spartacus · 16 August 2014, 12:38

Quote:

Originally Posted by Jason calleja

I have checked the cav plate and it is in proper height. I don't know how to attach the picture. so I think that I will have to try a higher pitc prop. if you can tell me how I will upload pict. thanks

To upload a picture, click 'manage attachments', then 'choose file' and search for the image, assuming its on your desktop or picture folder, etc. Once you've found the picture, select it, then click 'upload'. Allow it load, then close the window, and select 'preview post'. If all is well, hit reply.

Jason calleja · 16 August 2014, 13:03

Quote:

Originally Posted by spartacus

To upload a picture, click 'manage attachments', then 'choose file' and search for the image, assuming its on your desktop or picture folder, etc. Once you've found the picture, select it, then click 'upload'. Allow it load, then close the window, and select 'preview post'. If all is well, hit reply.

in my page I can't find manage attachments and when I click insert image it open a page to enter url address I can upload video but no pictures I don't know why

Jason calleja · 16 August 2014, 15:04

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alystra · 16 August 2014, 15:24

Quote:

Originally Posted by Jason calleja

I will check for the hight of the cavation plate.
The propeller selector on honda web side is indicating
that prop should be 21to23 pitc

I have a Honda BF90D on my 5.3m Humber destroyer. The Honda propeller supplied with the engine was a 19" pitch. It ventilated easily when trimmed up, just like you describe.

I changed to a Honda 21" propeller. This was a little better, but the engine was definately over propped and I could not get maximum revs.

I then fitted a Solas Rubex 3 19" pitch propeller. Problems solved. Max revs. Able to trim up to maximum and rarely get any ventilation.

Hope that helps.

Jason calleja · 16 August 2014, 16:01

I will try with another propeller to check if the problem is the prop supplied with the engine.

Jason calleja · 17 August 2014, 08:48

Quote:

Originally Posted by alystra

I have a Honda BF90D on my 5.3m Humber destroyer. The Honda propeller supplied with the engine was a 19" pitch. It ventilated easily when trimmed up, just like you describe.

I changed to a Honda 21" propeller. This was a little better, but the engine was definately over propped and I could not get maximum revs.

I then fitted a Solas Rubex 3 19" pitch propeller. Problems solved. Max revs. Able to trim up to maximum and rarely get any ventilation.

Hope that helps.

so if the propeller that was with the engine is defected is it the case to contact Honda dealer for a guarantee issue and claim for a replacement of the propeller? what do you think?

alystra · 17 August 2014, 10:11

Quote:

Originally Posted by Jason calleja

so if the propeller that was with the engine is defected is it the case to contact Honda dealer for a guarantee issue and claim for a replacement of the propeller? what do you think?

Not defective, just a slightly different design and obviously not suited to my particular boat. The dealer replaced it at no charge. I think engine, boat and propeller have to be matched and you can only tell by testing. The first prop was a 'first best guess'.

My dealer supplies many engines to commercial fish farm boats, which are not all fast RIBs. The original prop may have been more suited to those.

My Honda is the second engine on my boat, the original being a 90 hp Mercury, which I broke. That was supplied by Humber when the boat was built and was well matched. The Solas propeller looks very similar to the Mercury one. It seems to have more 'cupping' and thinner blades than the original Honda one. Perhaps that has made the difference.

Jason calleja · 17 August 2014, 16:11

I was making a search on what causes propeller to ventilate and while I found that something that causes air to enter into the prop I realised that I have the boat leader that keeps submerged and while I am driving it causes a lot of water splash. now I ask if this could cause the prop to ventilate?

Jason calleja · 17 August 2014, 16:36

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Have a look to the ladder and tell me what do you think?

Nos4r2 · 17 August 2014, 18:48

Wow, it even planes like that?!

Jason calleja · 17 August 2014, 19:42

Quote:

Originally Posted by Nos4r2

Wow, it even planes like that?!

I don't understand what do you mean by your comment??

kerny · 17 August 2014, 19:43

Pikey Dave · 17 August 2014, 19:59

Quote:

Originally Posted by Jason calleja

I don't understand what do you mean by your comment??

Nos is surprised that your boat will even plane with the ladder like that. It's not good & I would look at raising the ladder above the bottom of the hull before spending any money on the prop. The ladder could be the problem.

Peter_C · 17 August 2014, 20:05

Quote:

Originally Posted by Jason calleja

I was making a search on what causes propeller to ventilate and while I found that something that causes air to enter into the prop I realised that I have the boat leader that keeps submerged and while I am driving it causes a lot of water splash. now I ask if this could cause the prop to ventilate?

YES!!! It will cause severe turbulance. Remove the ladder and your issue should be gone.

You will probably gain a couple mph top speed too.