Outdrive question

[Guest]

I just fitted one of those hydroplane wing things to the outboard, and the tender now goes like a scalded cat, and is on the plane instantly. Question: I've seen the big versions for sale, but does anyone have any thoughts/experience on the wisdom or otherwise of fitting these to a pair of Volvo DP outdrives on a 30 footer?

 

[tr7v8]

Ummm, I've seen these and wondered what difference they'd make. Maybe an MBM equipment test? Kim????????

Jim
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[DepSol]

Dont even think about it, if you are having that much trouble getting on the plane then

1 get the right props
2 get your engine fixed
3 throw the fat Mother in law overboard

In reality get bigger trim tabs and use the leg and tabs together. Stainless Steel Props would certainly help in this dept aslo.

Please provide more info on dinghy and motor and hydrofoil used, thanks.

Dom

I am boating again ;-)

 

[EME]

One of the French mgazines did an equipment test on them on a reasonaby wide range of boats some months ago.

From memory they obtained stunning results with 3 of the hulls/outboard combiantions tested but one was an absolute disaster in that the hull involved became unstable and decreased performance.

As I recall their recommendation was to check VERY carefully with both suppliers before going this route to ensure that the como had been proven to work.

Then again I may be totally wrong and this post is a waste of space but I'm sure Kim can research their test for us.



A boat, a boat, my kingdom for a boat..

 

[duncan]

there is also the option of either bolted to the cavitation plate or to the skeg below the prop - I am sure they deliver different reactions. m8 has the latter on his Sprint with single volvo DP - but has never tried it without! ; and it's a dry berthed boat.

 

[Guest]

Clarification

OK, so the tender's a Quicksilver 270 Airdeck with a Yamaha 8hp 2-stroke. I use it as a tender (obviously) but also to tow the kids (6 & 8) around on an inflatable. I had to have arms like a gorilla, and sit in the bow to get it over the hump previously, but now it planes instantly, with no hump to get over.

The other boat is a F'line Targa 29, and is not difficult to plane, just slow with full fuel and water, and takes a bit of juggling with trim and tabs. I just thought it'd be nice to have the 'instant' response I get from the tender.

I spoke to Mike Vincent at South Coast Marine, and he said no-one was bringing in the necessary adaptors for the DP legs as they didn't want to get into a warranty war with Volvo. I've found a US supplier who does the fin and adaptor $61.50 per leg, and a UK one who quotes £83 + VAT for the same thing...

 

[DepSol]

Re: Clarification

If you want to pop on the plane quicker try SS props my boat goes much quicker and gets up much faster even loaded. I know its more expensive but much better at the end of the day. also got better fuel economy.

Dom

I am boating again ;-)

 

[Guest]

Bottomless pit

Have you looked at the cost of two sets of C7 duoprops???

Oh, and BTW, she's got a clean bottom, brand new A7 (ally) props, just been serviced, and is running on a mixture of St Peter Port white diesel and finest Soltron (bought in Christchurch, unfortunately...) Too early to make comments on fuel consumption, but definitely less smoke on startup.

 

[DepSol]

Re: Bottomless pit

Cheaper in C I as no VAT plus you could have bought your Soltron at a saving of £10 per litre whilst over here...a penny saved as they say.

If you do want SS I can get them for you at a significantly reduced price and less VAT if you want to collect.

If you are on A7s it will prob be C6s you'll need. How much are they in your area?

Dom

I am boating again ;-)

 

[Guest]

Re: Bottomless pit

Sorry, you're right, it is C6's, and the best I got was around £900 a set. Sorry for the gross disloyalty about the Soltron, but I bought it here planning to go to Cherbourg, but I got a txt from Alastair MacMaster mid channel, and we diverted and met him in St Peter Port, so the Guernsey thing was unplanned though highly enjoyable...

 

[martin]

White Diesel..Sounds good!

What is white Diesel and if it makes less smoke..where can I get it on the Thames>>

 

[ArthurWood]

As mentioned by others, for a 30ft boat, use trim tabs and trim outdrives.
Many years ago I fitted a Stingray hydrofoil to my 19ft Wellcraft w/Merc Alpha I. First time out, it got on plane very quickly but without warning the boat suddenly tilted about 45 deg to the right. When I throttled back it levelled out but it was a bit disconcerting to say the least. A short time after, the marina broke the Stingray and replaced it with an Attwood which gave great performance: fast on plane and lower planing speeds. However, I think the only manufacturers ( at least in the US) are now Doel with their Doel-fin, and Stingray. In summary, fit a fin to the anti-cavitation plate of o/boards and to I/Os to about 23ft boat length. Well worth the small expense.

 

[Gludy]

Re: Clarification

Why are stainless steel props better?


Paul

 

[DepSol]

Re: Clarification

Much stronger, flex and bend less under load, vibrate less have a slightly larger surface area with a better curve to the blade. AFAIK maybe someone else can come up with more answers,.... KIM???



Dom

I am boating again ;-)

 

[Guest]

Re: White Diesel..Sounds good!

White as opposed to red, i.e. full duty. You can buy white diesel at any filling station, but I doubt you'd like the price! The lack of smoke on start-up appears to be an effect of the Soltron...

 

[Guest]

Arthur,

I've used these things on outboards, and the flop to one side is (I think) the onset of chine walking, as a result of the arse end of the boat being too far out of the water. Do you have any idea why there should be a cut off at 23 foot or so? As mentioned earlier, I do use the trim and tabs, just looking for an easier life...

 

[adarcy]

Re: SS props

AFAIK because the metal is v much stronger than the usual alloy, they are much thinner blade cross section for the same prop size blade area and cupping. Therefore they cut through the water better and will give less cavitation.
I am on shakier ground than usual but AFAIK they do not <<have a slightly larger surface area with a better curve to the blade>> it is just a thinner blade. If you think of it, if they changed some of those criteria then you may not get a nearly like for like replacement.

 

[DepSol]

Re: SS props

Your probably right just when I put the two together for a comparison the eges of the SS seem to come out a few mill further. Dont really care how more so what as my boat gos soooo much better with them on.

Dom

I am boating again ;-)

 

[Col]

Re: SS props

A series props are aluminium with 4 blade uncupped rear prop.
C series stainless with 3 blade cupped rear prop.
The higher the number, the longer the pitch.
For best A to C swap, go for 1 No: less (ie) A6 =C5

<A target="_blank" HREF=http://www.arweb.co.uk/argallery/colspics> Cols Picture Album</A>

 

[ArthurWood]

Graham - don't know about chine walking, but it was unnerving at the time, especially as we were doing over 30kt at the time. I thought it was something to do with increased effective torque at the prop caused by the hydrofoil, but come to think of it, if that was the case, it should have leaned the other way with a clockwise rotating prop. It was so long ago, that I can't really remember which way it went!
As for 23ft, that was my number as I think that boats much over that length could or should have trim tabs. I think it's superfluous to add a hydrofoil if you already have tabs, as they basically do the same thing. If you have great difficulty getting on plane, you might be under-propped or under-powered (or have a lot of heavy junk aboard!).