Volvo Compressors/turbos again

[Guest]

Just bought a Fairline Targa 29 with AD31s, and I now understand why they also fit KAD32s (not that a boat with 32's was an option at the time). Nailing the throttles has little effect until they hit 3000rpm and the turbos spin up properly. Once through that barrier, she's fine, but the initial pickup is BAD (by comparison - I just got rid of a 23 footer with a 5.7 V8 petrol lump...).

Short of swapping out engines and legs at vast expense, does anyone know of a way of getting these lumps to act a little more lively? Aftermarket supercharging? nitrous injection? go faster stripes? getting out and pushing?

And before anyone asks, she's squeaky clean underneath and just been serviced.

 

[Scubadoo]

I think what you are experiencing is normal. Unfortuately you have been use to a V8.

My boat has one AD31 Turbo and also takes a while to wind up, but this has never bothered me. Your right it is just past the 3000rpm and then pulls away. Mine goes fairly quickly with just two of us onboard, however fully loaded with dive gear can be interesting. I find when needed to improve things a bit, I throttle all the way forward and at the same time set my trim tabs down, once on the plane raise the trim tabs.

If you are fully loaded, in my case when diving with four divers and all their gear (600kg ), my boat can struggle to plane, my trick is turn the boat with the tide and use trim tabs - at the same time steer small steps to get over the "hump".

I don't think you have any problems with your boat, just make sure those props are clean (I mean really clean), Stainless Steel props (I've heard) improves performance (pull away). I guess you could investigate adding compressors to the AD31s - that would make it a KAD32.

PS. Surely you realised this before you bought the boat during a test drive?

RM.

 

[Guest]

More or less what I had figured. I am still experimenting with the tabs - all the way down, they seem to make matters worse, but I had noticed that waggling the helm seems to help break her out.

Leg trim seems to make less difference than it did on previous, smaller boats, though anything over 1-2 deg trim up makes her porpoise (I have no frame of reference on this - the old Mercruiser trim gauge was analogue, so I dont know if +2 deg is high or not)

Any other suggestions, other than don't run with full tanks and a gaggle of people and gear?

 

[Scubadoo]

I would lower your trim tabs AFTER you have pushed your throttles all the way forward (not before). But again only do this if you have trouble to plane - a light load I don't bother. I also ensure my leg trim is at plus4 degrees (at it's maximum) and I generally (depending on conditions) cruise at +2, on particular calm sea it is more 0-minus1. Note the best way is to watch the speed on your GPS - if it increase as the leg is raised to a point where it decrease you know the best setting. Porpoise on my boat is when the sea & trim is not right for the speed (in my experience) i.e. engine throttle wide open - I tend to re-trim or slow down. To be honest I rarely go flat out as it is generally stresses the engine and can make it uncomfortable ride.

RM.

 

[Guest]

I would just sit and WAIT. When you get older you (normally)get wiser and enjoy the passage and dont need the accelaration...

Sorry, but in the first place you are in the wrong boat to do silly things. Sell it and buy a Sunseeker with the right engines.

The question about test driving before buying was painful, wasn't it?

Life is too short to spend on land

 

[Guest]

Point taken. We'd kind of grown out of the waterskiing phase, and into the longer range stuff, but it'd still be nice to have the best of both worlds.

As to the Sunseeker, I'd rather have the floating caravan ;-) Seriously, I couldn't afford a Sunseeker with the same accomodation, and I certainly don't have anywhere to keep one.

Test drive, yes... Should have paid more attention.

 

[Guest]

Thanks for the advice on tabs, but the stuff on leg trim seems back to front. From day one (in a 12 footer) I've always trimmed right in (i.e. -4 on the Volvo digital gauges) to get over the hump, then trimmed out for maximum speed. In a big sea, I've always trimmed in to bring the bows down to stop jumping/slamming.

Still, I'll ive it a go

 

[Guest]

Trimming an outdrive or outboard is the reverse from using trim tabs. In both situations you want the bow to come down to get over the hump. To do this you trim the engine/leg in but lower trim tabs to maximise "lift" at the stern.

Nick

 

[Guest]

Agreed. But the earlier post seemed to suggest doing the opposite with the leg trim, i.e. out to get over the hump. Confused of Christchurch...

 

[Scubadoo]

Sorry a typo, I should have said minus not plus, i.e. minus4 &minus2.

RM.

 

[Scubadoo]

Sorry, I meant the leg trimmed in as Nick has suggested. Don't want you getting frustrated this weekend by a silly typo!

RM.

 

[Guest]

Thanks for that. I was planning to do some more playing around anyway. All in the name of getting the best out of the boat, yoiu understand...

 

[PGD]

hi, I'm just in the process of refitting a fairline 23 with an ad31 as my v6 petrol split in the winter. I do most of my boating on the river so the top end speed wasn't an option so I didn't go for the kad 32 it's not as if you want to beat someone away at the lock gates ! - see MBM May/ June I think boat called red duster for a write up. I wouldn't wory about the boat not being on the plain within a boat length. what's the hurry?

Anyway you could try re proping her and if you have a DP E drive it's better than an SX so I'm told.