Repowering Sunseeker 31 Hawk

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Tom053

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Hi Everyone,
I have just purchased a 1996 31 Hawk with 5.8Fi petrol engines and wish to have it repowered with a pair of new Diesel engines. I have received conflicting advice as to whether the most suitable engines would be the Volvo d3 220 or a d4 260/300. My concern is would the additional weight and possibly dimensions of the d4 engine mean that the boat displaced too much and was very stern heavy. I understand this boat was most commonly fitted with a pair of KAD 42 engines.
The intended use if the boat is occasional and only very inshore use.
Thank you for your assistance.
 
Tom053 said:
Hi Everyone,
I have just purchased a 1996 31 Hawk with 5.8Fi petrol engines and wish to have it repowered with a pair of new Diesel engines. I have received conflicting advice as to whether the most suitable engines would be the Volvo d3 220 or a d4 260/300. My concern is would the additional weight and possibly dimensions of the d4 engine mean that the boat displaced too much and was very stern heavy. I understand this boat was most commonly fitted with a pair of KAD 42 engines.
The intended use if the boat is occasional and only very inshore use.
Thank you for your assistance.
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I'd do the maths first! If a re-power is necessary then to me, occasional inshore use suggests that petrol is not such a bad answer. And they sound good, too. Less capital cost & less weight are other considerations, of course. Yes petrol is expensive but figure out the delta before making the decision. On that point, have you considered a pair of re-built KADs might be the next best option? They would represent original engineering so de-risk the task and they may well be readily available from another re-power project. Good luck either way!
 
Gentlemanracer said:
I'd do the maths first! If a re-power is necessary then to me, occasional inshore use suggests that petrol is not such a bad answer. And they sound good, too. Less capital cost & less weight are other considerations, of course. Yes petrol is expensive but figure out the delta before making the decision.
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Well said Gentlemanracer, I agree with your thoughts
Fuel cost/price is not the overall issue when one considers the usage when boating for leisure purposes imho!
 
Crikey what would a pair of D4 260s cost,together with DPH drives and all that eletrickery ( which went wrong on my D4 260).?
 
Plenty of choices if you choose to repower and stay with gasoline: Indmar,Ilmor Crusader et al make suitable candidates.
 
Out Targa 30 with KAD32's (2 x 170hp) was good for close on 40 kts so I would have thought a pair of D3 220's would be loads. I'd be looking for a pair of used KAD32's or KAD4x's or even a single larger motor as was fitted to S28's.
 
As said above have you actually done the maths, pair of new Volvos will be £30-40K+, how much is a nice diesel 31 hawk worth £25-30K?
Sell the petrol boat and buy a nice diesel Windy :)

My own boat had been repowered by the previous owner with a pair of new Volvo diesels and outdrives, did 69hours then sold it to me for not much more than he paid for the engines, bargain for me but the worse investment he ever made.
 
A Windy 31 Tornado with twin-diesels can be had for £45k with some haggling so not a bad idea.

Otherwise I'd seriously consider a single D6-400 or Yanmar 6LY STP if you want to keep the boat. You might get £4k for the existing drives and engines depending on hours and condition etc towards purchase. Coastal rides usually have some salvage, rebuilds or bankrupt stock hanging about.
 
Stats007 said:
A Windy 31 Tornado with twin-diesels can be had for £45k with some haggling so not a bad idea.

Otherwise I'd seriously consider a single D6-400 or Yanmar 6LY STP if you want to keep the boat. You might get £4k for the existing drives and engines depending on hours and condition etc towards purchase. Coastal rides usually have some salvage, rebuilds or bankrupt stock hanging about.
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He wants reliability
 
Stats007 said:
A Windy 31 Tornado with twin-diesels can be had for £45k with some haggling so not a bad idea.
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+1

Stats007 said:
Otherwise I'd seriously consider a single D6-400 or Yanmar 6LY STP if you want to keep the boat.
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Jeez, he only wants to potter around on the river! I think something like a single KAD44-260 (as fitted to S28's) would be just enough to get him on the plane (S28 4400kg vs Hawk 31 3800kg) for occasional coastal use.
 
I think something has been lost in translation - inshore use I took to be coastal cruising. Why would you run a Hawk 31 on a river? If that's the case then keep the petrol engines as you'll only ever be doing 6 knots...
 
Stats007 said:
I think something has been lost in translation - inshore use I took to be coastal cruising. Why would you run a Hawk 31 on a river? If that's the case then keep the petrol engines as you'll only ever be doing 6 knots...
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My fault, I misread the OP's post. Still I don't think he needs much more than 300hp or so for a single motor.

Incidentally, I like Windy's but have never really understood that wasted rear space at the aft of the 31 cockpit. Did they do an option where that had a table? The Chichester one that's for sale suffers from space space issue.
 
Anyway, back to the original question, a couple of D3-220's at 360kg each would provide plenty of power, and wouldn't be too heavy, probably a bit lighter than the current V8's.

A single D6-370 would also fit the bill at 770kg, although it's very long - you'd have to check it would fit in the engine bay with enough access space around it, and any single engine option is going to require extensive modification to the transom.

A D4-260 weighs 660kg, so times two, that's going to be too heavy for the stern of a 3800kg boat without modifications to get the trim correct.

Of course, none of these options make any financial sense, unless you are planning to keep the boat for ever.

.
 
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Original twin KAD42s were about 1150kg a pair with legs and 460hp so a big single like the D6 or Yanmar makes sense if you want original performance but significant weight reduction. The D6 from transom shield to end is no bigger than a KAD42 - around 1200mm.

There's a pair of 42s ready to go on Apollo Duck:

http://apolloduck.net/228631

Also a D6 for £14k:

http://engines.apolloduck.co.uk/feature.phtml?id=196017
 
Stats007 said:
Original twin KAD42s were about 1150kg a pair with legs and 460hp so a big single like the D6 or Yanmar makes sense if you want original performance but significant weight reduction. The D6 from transom shield to end is no bigger than a KAD42 - around 1200mm.

There's a pair of 42s ready to go on Apollo Duck:

http://apolloduck.net/228631

Also a D6 for £14k:

http://engines.apolloduck.co.uk/feature.phtml?id=196017
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Those 42's would work well and would be in keeping with the age of the boat. Should be good for >40kts too.
 
petem said:
My fault, I misread the OP's post. Still I don't think he needs much more than 300hp or so for a single motor.

Incidentally, I like Windy's but have never really understood that wasted rear space at the aft of the 31 cockpit. Did they do an option where that had a table? The Chichester one that's for sale suffers from space space issue.
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I think the idea was a separate watersports area, though I believe owners found it a good "den" for young kids. Still, given the concept was not taken up by every other sports boat manufacturer suggests the idea didnt catch on !
 
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