HH 44 by the Wynss

[CaptainRivet]

Originally Posted by Pete7

That is a real shame. Other than Solara which are very expensive, about the only flexible panel I would entertain.

Pete

Try the offgridtec one i posted in #114, 100Euro for the 100W one to try is not a big loss if fail but a big gain when working...my approach to that.

[SandyLuke]

Originally Posted by CaptainRivet

And around 80-100kg additional weight per engine as you need a bigger saildrive too in sugar scoops weight plus the smaller run in their sweet spot when motoring.

Never heard an outremer owner complain the 30hp is too less. murph can for sure state for his mumbay if he wished he had more?
To your friedman link, the guy misses one major factor and thats losses, an engine running a bit above idle has much more losses (mechanical and thermal) then an engine running in its sweet spot means the losses are minimal on this engine at that spot. thats also how generators are operating geared so it always run in that sweet spot of the engine used for it.
And boat manufacturer, especially the performance cat ones, spec the engine so that one engine in normal condition does (i assume) 6kn at this sweet spot, for heavy condition add the power of 2nd engine running in that sweet spot to achieve that. For them its saving weight, if saildrives this additional weight is located at curcial end of the vessel. Saving 200kg costs the performance cat manufacturer for sure more to compensate then the step up in price installing a 50hp one (for condo its different).

And i know that, my Lavezzi has 2x50hp instead 2x20hp and does WOT 15kn on both engines (installed by former owner a motorboater, bought with 19h). On volvos the combo is 85kg heavier (but allows the maintenance/oilchange of the saildrive from engine room) which i compensated by getting rid of the 4x120AH lead in the engine rooms and putting a 1088AH LFP bank in much closer to center of the cat.
Motorsailing 1300-1500rpm i do with 1l per hour on one engine, there the bigger engine shines plus its hardly noticeable its running. but the 7kn on 1 engine motoring at 1800RPM is the same 3l per hour that is typical for the D2-50 on 44-48ft monos i know from charter and my buddy boat a dufour44 with 12t, yes i am 1kn faster. The 30hp 3 cylinder would do 2200RPM and around 6kn with 2.5-2.8l as other Lavezzi owner told me.

But even with extra weight, the fuel efficiency is better (all comparisons measured on boats). And the weight difference is not that great. A Yanmar 57hp with sail drive weighs 23kg more then a 40hp with sail drive. That's 46kg for the boat.

Adding 42kWh of Lithium batteries plus electric motors together adds a LOT more weight.

[JustMurph]

30s aren't undersized for a slippery 44' cat. It seems that the Wynns problem is being underpropped. Bigger engines won't help.

My 48' cat that's loaded at something like 9-10t, will motor on a single 3YM30 at just under 7 knots with a clean bottom, at 2600rpm (keep in mind the 3YM revs to 3500). We're using under 3L/hr.

Over 4L/hr on the seawind 1370 makes sense given it is significantly heavier and shorter.

Larger lower revving diesels are generally more efficient than smaller higher revving diesels, but they are also more efficient running at a heavier load. The reality is that there are a lot of variables here. Prop selection also plays a large part. E.g. over propping can see a pretty big increase in efficiency, but may limit your top end power a bit.

The conclusions that Phil Friedman arrives at in the article are right, he just gets there in a misleading way. They are:
- If you have two engines in the same family that weight the same but produce different power, get the more powerful one. Agreed.
- If you have two engines that produce the same power but have different weights, get the lighter one.

Putting a larger, heavier and more powerful engine in the boat that will never be run under high load, does not make sense.

[CaptainRivet]

Originally Posted by SandyLuke

But even with extra weight, the fuel efficiency is better (all comparisons measured on boats). And the weight difference is not that great. A Yanmar 57hp with sail drive weighs 23kg more then a 40hp with sail drive. That's 46kg for the boat.

Adding 42kWh of Lithium batteries plus electric motors together adds a LOT more weight.

Thats a 4 cylinder with a 4 cylinder but 30hp is a 3 cylinder with the smaller saildrive and thats 85kg difference engine+saildrive to the 4 cyclinder.
With volvo you can have 40 to 85hp with basically the same engine and saildrive, above 50 hp its with turbo which i would avoid at all costs.

[Matt Johnson]

Dazcat specs a 21hp Yanmar for a 44' catamaran. And there are a few Oram 44 and Schionnings running around with 20hp outboards

Everyone here is correct. It's not fuel use that's dictating these engines, it's weight of the system and what HP is actually needed to drive these slimmer hulls.

[CaptainRivet]

Originally Posted by JustMurph

30s aren't undersized for a slippery 44' cat. It seems that the Wynns problem is being underpropped. Bigger engines won't help.

My 48' cat that's loaded at something like 9-10t, will motor on a single 3YM30 at just under 7 knots with a clean bottom, at 2600rpm (keep in mind the 3YM revs to 3500). We're using under 3L/hr.

Over 4L/hr on the seawind 1370 makes sense given it is significantly heavier and shorter.

Larger lower revving diesels are generally more efficient than smaller higher revving diesels, but they are also more efficient running at a heavier load. The reality is that there are a lot of variables here. Prop selection also plays a large part. E.g. over propping can see a pretty big increase in efficiency, but may limit your top end power a bit.

The conclusions that Phil Friedman arrives at in the article are right, he just gets there in a misleading way. They are:
- If you have two engines in the same family that weight the same but produce different power, get the more powerful one. Agreed.
- If you have two engines that produce the same power but have different weights, get the lighter one.

Putting a larger, heavier and more powerful engine in the boat that will never be run under high load, does not make sense.

Exactly the answer i expect Murph...

If you have two engines in the same family that weight the same but produce different power, get the more powerful one. Agreed. => i have to add without a turbo and common rail...

What all the performance cat manufacturers do in this <=48ft cats is using a lighter 3 cylinder 30hp instead 80-100kg more 4 cylinder+bigger saildrive or shaftgearbox.

I have to admit, being overpowered on engine side gives you a lot more flexibility and also saftey...my vessel wouldn’t have survived the 8m pyramid rough wave with 2x20hp but 2x50hp on WOT gave me the additional speed to make it over its top and only part of it collapsing on one of my hulls...the 55ft mono next to me didn't and got a complete deck swipe (nothing was there anymore no dogger no mast,no solar arch no dingy...boat is a total loss as structure got completely crashed too) and that no people were dead is due to the experienced skipper (everybody was down in salon) on that 55 which i towed into next habour afterwards.

Screwing up the tide calculation in a tight weather window going through straight of Gibraltar the 2x50hp on 2300RPM allowed me to motor through with 6kn having 5kn of current against me...forget doing that with 2x20hp...

[SandyLuke]

Originally Posted by JustMurph

30s aren't undersized for a slippery 44' cat. It seems that the Wynns problem is being underpropped. Bigger engines won't help.

My 48' cat that's loaded at something like 9-10t, will motor on a single 3YM30 at just under 7 knots with a clean bottom, at 2600rpm (keep in mind the 3YM revs to 3500). We're using under 3L/hr.

Over 4L/hr on the seawind 1370 makes sense given it is significantly heavier and shorter.

Larger lower revving diesels are generally more efficient than smaller higher revving diesels, but they are also more efficient running at a heavier load. The reality is that there are a lot of variables here. Prop selection also plays a large part. E.g. over propping can see a pretty big increase in efficiency, but may limit your top end power a bit.

The conclusions that Phil Friedman arrives at in the article are right, he just gets there in a misleading way. They are:
- If you have two engines in the same family that weight the same but produce different power, get the more powerful one. Agreed.
- If you have two engines that produce the same power but have different weights, get the lighter one.

Putting a larger, heavier and more powerful engine in the boat that will never be run under high load, does not make sense.

Agreed, the Wynns problem won't be helped by bigger engine (its a prop compromise issue).

Comparing between boats given different weight, hull shape, length, props etc. is a difficult comparison. But I have seen that on a Seawind 1260 (going from 29hp to 40hp) that the bigger engine is more fuel efficient (the 1260 coming in at around 9.5t). Also a lot less noisy and lower vibrations since the engine revs lower at same cruising speed.

[Cheyne]

When we repowered our Lagoon 380 we went from Volvo D1-30's to Yanmar 3JH40's. I always felt the 380 was underpowered for our use which includes a lot of river and ICW time. We use the same amount of fuel as with the D1-30's, but can motor about 2 to 2.5 knots faster than we did before. Now our D1-30's were almost 20 years old and engine hours were unknown except that last number on the gauge was 3400, but the previous own said that dated back to 2008. Plus we worked with Maxi Prop and they put 18" 3 blade on instead of the old 12" 2 blade the boat had. We also had them setup as counter rotating.

Cheyne

[CaptainRivet]

Originally Posted by Cheyne

When we repowered our Lagoon 380 we went from Volvo D1-30's to Yanmar 3JH40's. I always felt the 380 was underpowered for our use which includes a lot of river and ICW time. We use the same amount of fuel as with the D1-30's, but can motor about 2 to 2.5 knots faster than we did before. Now our D1-30's were almost 20 years old and engine hours were unknown except that last number on the gauge was 3400, but the previous own said that dated back to 2008. Plus we worked with Maxi Prop and they put 18" 3 blade on instead of the old 12" 2 blade the boat had. We also had them setup as counter rotating.

Cheyne

Sounds like my 40ft Lavezzi, before the 2020 and now 2xD2-50 with 18x13 3 blade Flex-o-fold. But my engines where originally both clockwise so Flex-o-fold said i should keep it this way. The Lagoon 380 is also clockwise on both.
Got told you need to change something in the saildrives so it now the BB turns anticlockwise and you could mount that counter rotating prop.
What did you change and what was the impact of doing it?

[Kinkircating]

Does anyone know if the Wynns or HH has shared what the displacement of the HH44 actually ended up being. They state its 21,070 pounds or 9.56T, and their President Seth takes pride in mentioning that HH puts this in their build contracts as a guarantee (which they should). Just figured on this would have been information they would share what it really came in at...unless maybe she's a tad heavier than projected. Also, a reason why it's good to be hull #10 or later so the builder has had some time to work stuff out and optimize.

[Cheyne]

On the SD60 you make a change with a leaver. You set it to clockwise or counter clockwise. On the Max Prop you take the cover off and remove a set screw then remove a clicp to slide over the lever that sets the direction and put it back together. It took about 10 minutes to do both sides.

Cheyne

[CaptainRivet]

Originally Posted by Cheyne

On the SD60 you make a change with a leaver. You set it to clockwise or counter clockwise. On the Max Prop you take the cover off and remove a set screw then remove a clicp to slide over the lever that sets the direction and put it back together. It took about 10 minutes to do both sides.

Cheyne

Thanks, wish it would be that easy on the Volvos.
And Flex-o-fold its a completely different hub due to their GM.
so you have one clockwise and one anti-clockwise what did change compared to before?
My Flex-o-fold don't really fit in 18x13 and i had an upfront agreement can hand them back and swap them.
Size should be 17x12 and i could have one anti-clockwise. What i figured on mine is when i motorsail that i can put one engine on that helps keep course close haul 45 degrees and autopilot is hardly correcting. Do i use the other engine the autopilot/rudder needs to be corrected 5-10 degress to keep the same course and also slows you down 0.5kn due to this correction.
If i am doing the same at 335 degrees close haul i have to correct the 5-10 degrees on each of the engine. If i would have one counter clockwise and on anti-clockwise i would have the same then at 45 degrees close haul. Also cat would keep straight line course with both engines on better. Am i right?

[donradcliffe]

Originally Posted by SandyLuke

Sure, smaller engines are adequate, but a bigger engine will give you better fuel efficiency.

I regularly crew on Seawind 1260 and it comes with 29hp or 40hp option. The boats with 40hp engines consume less fuel under all conditions then the 29hp boats.

Take a read of the below:

https://www.linkedin.com/pulse/rated...hil-friedman-/

If the author of that article was in my engineering class I would give him an F for that paper. So many things wrong with what he says.

[Cheyne]

The boat almost always track straight. On the ICW it really pays off. Also when moving around in tight spots. My only problem is personal with the Max Props. I forget to feather them. Just put them in reverse for a short time, normally 30 seconds and then back to netural does it. You notice the difference right away. My wife put a label above the engine controls to remind me.

Cheyne

[CarlF]

I’ve been told that counter rotating props make no difference on a sailing cat because they are so far apart. On a powerboat with closely placed screws the water off the inward spinning props can lift the stern a little improving planing. They can also be used to “walk” a monohull stern one way or the other when docking.