Prop Spinning Out in Rough Weather

[benhben]

I took my new F-RIB 330 and Suzuki 6HP 4 stroke out to windermere last week. The weather was awful and the water had a fair bit of chop but I was keen to test the new boat.

One issue encountered was that the prop on the suzuki was spinning out and loosing all forward power in the waves. It resulted in not much more than displacement speed. I'm assuming the prop was simply coming out of the water as the boat went up and down.

Is this normal in rough weather? The trim on the motor looked ok.

I've been out in similar conditions in my Honwave T38 and 15hp tohatsu without these issues.

Is the F-Rib more prone?

I think it would have been quie unsafe if I had this out at sea against tide.

Thanks
Ben

[Pikey Dave]

Originally Posted by benhben

I took my new F-RIB 330 and Suzuki 6HP 4 stroke out to windermere last week. The weather was awful and the water had a fair bit of chop but I was keen to test the new boat.



One issue encountered was that the prop on the suzuki was spinning out and loosing all forward power in the waves. It resulted in not much more than displacement speed. I'm assuming the prop was simply coming out of the water as the boat went up and down.



Is this normal in rough weather? The trim on the motor looked ok.



I've been out in similar conditions in my Honwave T38 and 15hp tohatsu without these issues.



Is the F-Rib more prone?



I think it would have been quie unsafe if I had this out at sea against tide.



Thanks

Ben

Did you try lowering the trim pin? Assuming it’s not at it’s lowest setting already. On a boat with power trim, you’d lower the trim in rough seas to avoid “blowout”. I experienced the same issues with my 20hp on the Volaire when it got lumpy. Lowering the trim reduced the problem.

[jeffstevens763@g]

I found with my vanguard with the cav plate level with the keel it did similar I took the block out lowered the engine straight on the transom top sorted it. Of course loading can be the problem. Gurnard will be along soon he has an Frib

[Steve509926]

I had exactly the same problem with my SD360 earlier in the year on Ulleswater when I was solo (normally 2 up with a dog) It was very rough, short chop. I dropped the trim pin to the first hole as PD has suggested and found that it made a massive difference.

[benhben]

Originally Posted by Steve509926

I had exactly the same problem with my SD360 earlier in the year on Ulleswater when I was solo (normally 2 up with a dog) It was very rough, short chop. I dropped the trim pin to the first hole as PD has suggested and found that it made a massive difference.

Thanks for the advice. Ill set up in the garden and see what trim pin the engine is sat on. My on the water check was simply whether the motor was trimmed vertical or on an incline.

[Pikey Dave]

Originally Posted by benhben

Thanks for the advice. Ill set up in the garden and see what trim pin the engine is sat on. My on the water check was simply whether the motor was trimmed vertical or on an incline.

No need to set up, just have a look at the engine transom bracket & see which hole the pin’s in. If it’s not in the bottom hole (the one nearest the transom) you can drop it down the next time out & give it a try.

[Matt]

The other thing with sibs is that they tend to have a very flat hull so can easily get quite a bit of air under the hull. A rescue boat I used to use with a 50 on was terrible if someone hadn't pumped up the bow V section chamber as hard as possible.

[The Gurnard]

I must admit Im surprised to hear the F Rib cavitate Benhben. ?

Its transom is 15” and a short shaft is normally around 17” ?

Have you raised the outboard with packing pieces ? If so..that could be your issue. I keep mine in second hole and never move it and not once suffered cavitation despite going to sea is all sorts of conditions.

I do have to go at displacement speed in the rough though or I would be bounced out the boat..its hard flat bottom is a back jolter. Mine is a 6HP Yamaha though, so don’t know about Suzuki’s ? Mine is 2.75m size but my bro has the 3.30 size and no issues with his either.

Cant help much more except perhaps say ... distribute your weight to assist sort it.

[Matt]

Whether SIB or RIB, sub 3 metre boats with a 10hp or so on are a lot of fun aren't they.

[The Gurnard]

Originally Posted by Matt

Whether SIB or RIB, sub 3 metre boats with a 10hp or so on are a lot of fun aren't they.

Hi Matt..yup..I think I have had more fun out the wee F Rib and 6HP than any other boat I have ever owned. Its so easy to carry down bankings and across seaweed shores etc . Its also my chosen winter boat because of how easy it is to use and Im still out every other day despite the clock going back.

Today I was off at 7am and out until 3.30pm on Loch Etive..its absolutely stunning there just now.

This is a video from last week ..another stunning day ..on Loch Leven ..and an impossible launch for anything but a lightweight setup.

https://www.youtube.com/watch?v=qCeSM1zZrEs

[Matt]

I've got a Dell Quay Jaunty on the drive I keep meaning to rebuild. Obvs a hardboat, but the same principle applies. Light, planes well, carefree & fun boating.

[jeffstevens763@g]

Great that Donny never put the boat in but it’s a nice drive around

[Steve509926]

Nice video Donny. Kayaked and sailed few times on Loch Leven launching from the Ballachulish Marina. It looked very calm under the bridge! obviously timed it just right, or just wrong depending on which way you look at it