Lucky to get home !!

[Refueler]

My Primor 24 is to say the least - a bit stern heavy ... having had her original 4cyl 130hp VP engine removed and a 6cyl 170HP VP engine fitted. Even when sitting idle alongside - she has a visible stern trim.

The owner who did this is obviously the one who also then fitted trim tabs to try and compensate ...

I have made a couple of threads on the trials of getting this boat to behave.... she being ultra sensitive and often diving off to one side or another when increasing speed .. chine walk ?

One of the factors that has become apparent with a number of runs - is the varying fuel consumption.

If there are just two of us on board - she trims and runs well ... the tabs can be used to bring the bow down .. get a planing attitude ... consumption in the 15 - 25knot range of about 1litre per knot per hour.

BUT have a couple of people sitting in the stern and boy - that blows the numbers out the door !

First - the trim tabs have great difficulty getting the bow down ... the stern stays 'dug in' ... opening the throttle just gets the engine showing by sound its effort to get things moving ... but she just plain fails to get up and go.

At 4500 rpm with myself and one other .. we can average 15 - 17kts .... with 25kts if we open up throttle more.

Yesterday as with another day when we had 4 - 5 people incl myself - she averaged 8kts at 4500rpm.

Yesterday though was a real test of nerves ... I started with both tanks each holding about 45ltrs. This should give about 3 - 3.5hrs if I push the throttle.

I decided as the guests had never been on the river ... to risk going a little further upriver. We turned round after 1hr 20mins. At 2hrs 05mins ... engine cut out. Dip of tanks showed port tank empty and stbd tank about 20ltrs left.

With the trim tabs unable to work as the speed was low - the boat had been heeling about 5 degrees to stbd ... so the port tank had drained first.

Closed of the port tank and restarted engine ...

I kept quiet to the guests - not wanting them to be alarmed .... but I was seriously worried that we would not get back to the mooring ... I kept the engine down about 3000rpm .. burbling along at about 6.8 - 7kts ....

We made it home with about 12 ltrs left in the tank.

This is the first time I did not use my usual safe system. usually I gauge tanks and run only one tank. The tank going out is the one with least fuel in ... keeping the greater for going back. I stupidly assumed that 90 litres would be more than enough for a ~2.5hr trip .... expecting to still have about 30ltrs left after.

And people wonder why I still have sailboats !!

OK - I have a possible answer that may help the boats trim ... in the fwd section is a freshwater tank that is empty ... my thoughts are to fill it up and get that bow down ... as well as transfer as much gear as possible into fwd cabin space ... (suggestions to wife and friends to lay on the fwd cabin top / deck fell on deaf ears !)

 

[LittleSister]

Yes, I was going to suggest adding weight forward before getting to your last paragraph. I am not familiar with mobos, but imagine that even though generally one wants to avoid having uneccesary weight, if you are suffering such severe consequences from being down by the stern, then the advantage of doing so will, er, outweigh the disadvantages.

Filling the water tank is an easy win.

Moving gear to fwd cabin is good, too. Remember that moving the heaviest gear (rather than lightweight stuff) will be most effective, that the nearer the bow the more effective any given weight is at balancing your 'droopy stern', and (likely somewhat in tension with the last point) ideally the extra weight should be as low down as possible.

My own sailing boat is a bit stern down due to an above standard power and very heavy engine, an extra battery, and calorifier added behind it well aft. I discovered the previous owner had added large lead ingots below the cabin sole in the forecabin!

p/s Narrow squeaks are one of the better ways our errors and lackadaisical habits are highlighted! You probably won;t make the same mistakes again. At least you weren't piloting an airliner with nearly 200 passengers aboard that finally managed to land with only 6 minutes' worth of fuel left, as happened the other day in the UK. I imagine that Captain will be getting a serious carpeting, but it could have been horrifically worse.

 

[stelican]

The chine walking may increase if you add weight in the bow.

 

[Refueler]

Yes, I was going to suggest adding weight forward before getting to your last paragraph. I am not familiar with mobos, but imagine that even though generally one wants to avoid having uneccesary weight, if you are suffering such severe consequences from being down by the stern, then the advantage of doing so will, er, outweigh the disadvantages.

Filling the water tank is an easy win.

Moving gear to fwd cabin is good, too. Remember that moving the heaviest gear (rather than lightweight stuff) will be most effective, that the nearer the bow the more effective any given weight is at balancing your 'droopy stern', and (likely somewhat in tension with the last point) ideally the extra weight should be as low down as possible.

My own sailing boat is a bit stern down due to an above standard power and very heavy engine, an extra battery, and calorifier added behind it well aft. I discovered the previous owner had added large lead ingots below the cabin sole in the forecabin!

p/s Narrow squeaks are one of the better ways our errors and lackadaisical habits are highlighted! You probably won;t make the same mistakes again. At least you weren't piloting an airliner with nearly 200 passengers aboard that finally managed to land with only 6 minutes' worth of fuel left, as happened the other day in the UK. I imagine that Captain will be getting a serious carpeting, but it could have been horrifically worse.

My 25ft motor-sailer has concrete set under the forecabin boards due the large engine .... 43hp Perkins 4-107 ...

 

[Refueler]

The chine walking may increase if you add weight in the bow.

Maybe ... but given the trim of the boat - I reckon its worth trying at least ... I can't imagine it being worse than I already have ...

 

[aerobat]

I can't imagine it being worse than I already have ...

Because she will develop "bow surfing" and list hard over trying to plane out .

 

[stelican]

Maybe ... but given the trim of the boat - I reckon its worth trying at least ... I can't imagine it being worse than I already have ...

Yes but don't pour concrete in

 

[Hot Property]

My Primor 24 is to say the least - a bit stern heavy ... having had her original 4cyl 130hp VP engine removed and a 6cyl 170HP VP engine fitted. Even when sitting idle alongside - she has a visible stern trim.

The owner who did this is obviously the one who also then fitted trim tabs to try and compensate ...

I have made a couple of threads on the trials of getting this boat to behave.... she being ultra sensitive and often diving off to one side or another when increasing speed .. chine walk ?

One of the factors that has become apparent with a number of runs - is the varying fuel consumption.

If there are just two of us on board - she trims and runs well ... the tabs can be used to bring the bow down .. get a planing attitude ... consumption in the 15 - 25knot range of about 1litre per knot per hour.

BUT have a couple of people sitting in the stern and boy - that blows the numbers out the door !

First - the trim tabs have great difficulty getting the bow down ... the stern stays 'dug in' ... opening the throttle just gets the engine showing by sound its effort to get things moving ... but she just plain fails to get up and go.

At 4500 rpm with myself and one other .. we can average 15 - 17kts .... with 25kts if we open up throttle more.

Yesterday as with another day when we had 4 - 5 people incl myself - she averaged 8kts at 4500rpm.

Yesterday though was a real test of nerves ... I started with both tanks each holding about 45ltrs. This should give about 3 - 3.5hrs if I push the throttle.

I decided as the guests had never been on the river ... to risk going a little further upriver. We turned round after 1hr 20mins. At 2hrs 05mins ... engine cut out. Dip of tanks showed port tank empty and stbd tank about 20ltrs left.

With the trim tabs unable to work as the speed was low - the boat had been heeling about 5 degrees to stbd ... so the port tank had drained first.

Closed of the port tank and restarted engine ...

I kept quiet to the guests - not wanting them to be alarmed .... but I was seriously worried that we would not get back to the mooring ... I kept the engine down about 3000rpm .. burbling along at about 6.8 - 7kts ....

We made it home with about 12 ltrs left in the tank.

This is the first time I did not use my usual safe system. usually I gauge tanks and run only one tank. The tank going out is the one with least fuel in ... keeping the greater for going back. I stupidly assumed that 90 litres would be more than enough for a ~2.5hr trip .... expecting to still have about 30ltrs left after.

And people wonder why I still have sailboats !!

OK - I have a possible answer that may help the boats trim ... in the fwd section is a freshwater tank that is empty ... my thoughts are to fill it up and get that bow down ... as well as transfer as much gear as possible into fwd cabin space ... (suggestions to wife and friends to lay on the fwd cabin top / deck fell on deaf ears !)

Weight is everything on a powerboat. I'm not sure what your boat weighs but I would guess 2.5 to 3 tons.

170 hp isn't a great deal for that weight and that's assuming the engine is still producing it's stated output.

I doubt you are travelling fast enough for chine walk either.

If you have a sailboat then adding weight isn't an issue for yachts. I'd have a good rootle through your lockers and remove non essential items.

A common way of getting a boat on the plane is to ask guests to move forward ( into the cabin) for a few moments whilst you spin up.

Good luck!

 

[julians]

we said this in the last thread you started about trim tabs, but I'll say it again.

Move any moveable weight forwards if possible, get rid of anything unnecessary, distribute your guests more evenly throughout the boat.

experiment by lowering the outdrive trim - I think yours is not on the fly adjustable trim, so you'll have to find a compromise , but trimming the drive all the way in/down will provide more lift at the stern at the expense of a higher top speed/better fuel economy.

if after you all this its no better (or there is nothing to move/remove etc) , then the boat is probably not suitable for how you want to use it.

Maybe you can also make things a bit better by fitting something like a doelfin to the outdrive to provide more lift at the stern, but you might just be throwing good money after bad with that.

Davis Doel-Fin Hydrofoil | Force 4 Chandlery

 

[Refueler]

Weight is everything on a powerboat. I'm not sure what your boat weighs but I would guess 2.5 to 3 tons.

170 hp isn't a great deal for that weight and that's assuming the engine is still producing it's stated output.

I doubt you are travelling fast enough for chine walk either.

If you have a sailboat then adding weight isn't an issue for yachts. I'd have a good rootle through your lockers and remove non essential items.

A common way of getting a boat on the plane is to ask guests to move forward ( into the cabin) for a few moments whilst you spin up.

Good luck!

She displaces as per specs with the AQ130 VP engine (4 cyl) 1.3 tons .... but having the 6cyl AQ170 VP in her - probably more like 1.5 tons.

When on trailer - the suspension is not pressed as if she is heavier .. trailer is for up to 3T

Add 4 people and a bit of gear .. say 400kg .. but they insist on sitting at the stern .. they are not boaters and don't like the narrow side deck ..

As to speed at which she dives off to side .. chine walk .. usually as she passes 15kts or more ... if I have only myself / 1 other on board - I have solved that and can get her to 23 - 25kts without much hassle .. having taken on board previous threads advice etc and tried all out.

The problem here as I see it - is trying to get that bow down and ... let her get going .. so far when 4 - 5 people on board - she digs in her stern ..

 

[Refueler]

we said this in the last thread you started about trim tabs, but I'll say it again.

Move any moveable weight forwards if possible, get rid of anything unnecessary, distribute your guests more evenly throughout the boat.

experiment by lowering the outdrive trim - I think yours is not on the fly adjustable trim, so you'll have to find a compromise , but trimming the drive all the way in/down will provide more lift at the stern at the expense of a higher top speed/better fuel economy.

if after you all this its no better (or there is nothing to move/remove etc) , then the boat is probably not suitable for how you want to use it.

Maybe you can also make things a bit better by fitting something like a doelfin to the outdrive to provide more lift at the stern, but you might just be throwing good money after bad with that.

Davis Doel-Fin Hydrofoil | Force 4 Chandlery

The outdrive trim is adjustable - its electro-mechanical. But on advise from Volvo Penta in Riga and mechanics locally - I'm told that the drive is not designed to run raised for any appreciable periods .. only basically to clear shallows. They even advised me not to raise the drive when boat is moored or stored ashore - to prevent the bellows cracking with the curvature .. right or wrong - I bow to their better knowledge. One actually questioned the logic of the guy who swapped the engine ... saying he's not surprised boat has such behaviour .. he reckoned the 130 should have been more than enough for the boat. The designer / builder of the boat certainly thought so !!
One of the problems with getting original data other than the orignal info paperwork - is the boat is a one-off build. The builders produced many 19's, 21's etc ... but this 24 was to order for a Swedish Naval Officer ..
Changes were then made by next owner .. replaced the pneumatic trim tabs with manual hydraulic ... swapped out the engine .. swapped out the outdrive ...
The other adjustable of course is the pin that sets the drive angle when fully down .. this is full max down position .. so I cannot get any more vertical !

It really anoys - because when she runs and planes - she is sweet ... but when she does this - I could easily get rid and get another boat !



Soon she will be lifted out and we will be studying her again .. see if anything can be done.

 

[oldgit]

Back when Nelson was a lad...
Had Princess 33 with a pair of AQD40B and 280 T outdrives.
The 40B were bullet proof and had well over 3500 hours on the clock when sold on.
The 280 T was Volvos "Beta test" on the unsuspecting boating public with an attempt to inflict outdrives with a hydraulic trim and tilt system.
Available in both single prop and duo prop format and with a modified transom assembly to accommodate the rams.
It did work, sort of, but a nightmare to de-barnycle and a constant war of corroding rams and leaking hydraulics plus all the usual outdrive failings ie, gearchange seals prop seals etc etc. but still required a set of trim tabs to get the bow down.
Being on outdrives it of course needed a auto pilot to correct the annoying wandering all over the place on a long reach.
Any who, the added weight in the stern caused both the steering fork seals on the outdrives to be under the water most of the time when stationary .
It was possible using both trim and tilt plus trim tabs to get the nose down when under way and achieve on one occassion a heady 15/16 knots (ish) .
VP of course stopped producing bits for this little "experiment" not long afterwards replacing it with the 290.
Do recall importing an entire 280T transom assembly from the "States" just in case.

 

[Boathook]

Possibly major work, but could the outdrive be removed and a wedge made to alter it's angle on the transom ? Might need to alter drive shaft length though depending upon angles, etc.

 

[julians]

I'm told that the drive is not designed to run raised for any appreciable periods .. only basically to clear shallows. They even advised me not to raise the drive when boat is moored or stored ashore - to prevent the bellows cracking with the curvature .. right or wrong - I bow to their better

I'm not saying to raise the outdrive, I'm saying to lower it, if it's already in the lowest setting then that's fine and there's nothing more you can do from an outdrive trim point if view to improve planing ability.

Lowering the outdrive will point the prop slightly more down towards the seabed, giving an angle of thrust that lifts the stern of the boat. It will help with planing, but then once you're up to speed it will make bow steer worse (which is what I think you are experiencing when the boat veers to one side, not chine walking which is when the boat tips left to right alternately) ,top speed will Not be as high as it could be(if you could then trim the drive up), and fuel economy will be lower.

if you're already on the lowest setting, maybe try the drive on one hole higher with the pin - it wont help with your problem of getting on the plane when fully loaded, but it might improve/reduce the bow steer once you are planing.

all this advice assumes that the lowest trim of the outdrive isnt ridiculous of course - anything extreme (either up or down)will be a problem, but I'm assuming the lowest trim position isnt extreme. If it is extreme (appreciate you might not know what is extreme or not) maybe you just need to experiment with different trim angles and find one that works best.

When the boat is out of the water can you post a photo showing the angle of the propellor versus the water line?

 

[oldgit]

P

Thread 'WHAT IS CHINE RIDING?'

19 Aug 2008

Can someone explain what this is?

• penpal
• Replies: 13
• Forum: Motor Boat Forum

 

[Refueler]

Back when Nelson was a lad...
Had Princess 33 with a pair of AQD40B and 280 T outdrives.
The 40B were bullet proof and had well over 3500 hours on the clock when sold on.
The 280 T was Volvos "Beta test" on the unsuspecting boating public with an attempt to inflict outdrives with a hydraulic trim and tilt system.
Available in both single prop and duo prop format and with a modified transom assembly to accommodate the rams.
It did work, sort of, but a nightmare to de-barnycle and a constant war of corroding rams and leaking hydraulics plus all the usual outdrive failings ie, gearchange seals prop seals etc etc. but still required a set of trim tabs to get the bow down.
Being on outdrives it of course needed a auto pilot to correct the annoying wandering all over the place on a long reach.
Any who, the added weight in the stern caused both the steering fork seals on the outdrives to be under the water most of the time when stationary .
It was possible using both trim and tilt plus trim tabs to get the nose down when under way and achieve on one occassion a heady 15/16 knots (ish) .
VP of course stopped producing bits for this little "experiment" not long afterwards replacing it with the 290.
Do recall importing an entire 280T transom assembly from the "States" just in case.

The drive on my Primor is the AQ280 .... not a T version. It has electro-mechanical raise / lower ... as some reckon - a washing machine motor turning a pinion on a worm drive rod. The rod extends out transom near vertically onto a pad on the drive ... this pad has two functions ... one to release the drive astern lock and to raise / lower the drive.
VP and local mechanics told me - it is not designed to take the power of that drive and is only there for raising / lowering for low speed shallow transit / raising to beach the boat basically.

When I had the exhaust / water collector elbow replaced - guy also refurbished the lift system. Motor was found to have one wire coil failed - rewound, pinion was found to with lost thread to ride up / down worm rod - guy 3D printed replacement, wiring and connection box found to be heat damaged from being too close to manifold - wire continuity checked and each wire insulated and then fixed away from manifold ...

You'll love this : Everything except the new exhaust item - 110 euros. Add the exhaust item ... 510 euros total.

 

[Refueler]

I'm not saying to raise the outdrive, I'm saying to lower it, if it's already in the lowest setting then that's fine and there's nothing more you can do from an outdrive trim point if view to improve planing ability.

Lowering the outdrive will point the prop slightly more down towards the seabed, giving an angle of thrust that lifts the stern of the boat. It will help with planing, but then once you're up to speed it will make bow steer worse (which is what I think you are experiencing when the boat veers to one side, not chine walking which is when the boat tips left to right alternately) ,top speed will Not be as high as it could be(if you could then trim the drive up), and fuel economy will be lower.

if you're already on the lowest setting, maybe try the drive on one hole higher with the pin - it wont help with your problem of getting on the plane when fully loaded, but it might improve/reduce the bow steer once you are planing.

all this advice assumes that the lowest trim of the outdrive isnt ridiculous of course - anything extreme (either up or down)will be a problem, but I'm assuming the lowest trim position isnt extreme. If it is extreme (appreciate you might not know what is extreme or not) maybe you just need to experiment with different trim angles and find one that works best.

When the boat is out of the water can you post a photo showing the angle of the propellor versus the water line?

I understood your post .. I was just remarking that the drive trim facility is not as VP told me for trimming the drive when in use.

Yes the drive is down at max trim .. I cannot see any way to increase that. I would be extremely reluctant to start adding wedges etc as another suggests.

Raising by one hole ? because of the bigger engine and increased stern draft - its not so easy to get at the pin .. its really a lift out job. Boat will be lifted maybe end of month - so can look then ... but any test will then have to wait till spring.

Drive angle vs water line ? Yes I plan that anyway ..

Attached is the original sales blurb for it ... with sketched line ..



OK - just took a couple of photos to show that she really does sit down at stern even when no-one on board.





I may be wrong - but I believe that the drive should not so buried like that when at rest and no-one on board. That at least a reasonable part of the drive head should be above water ?


OK ... more info :

There is little on board in terms of gear ... the anchor is a 5lb grapnel .. and sits in the locker under cockpit sole. That can go fwd into the bow locker. The behind transom bench backrest - are mooring ropes only. Can always reduce the number or put fwd as well - leaving just a couple in stern.
I have been considering adding a proper stemhead fitting and anchor .. but the boat has no naval pipe or chain locker. I am loathe to start cutting the deck etc. But it can be looked at. Up to now - I have used a small fluke anchor with Ankoralina reel ...
The sales page - you can see thw water tank right in the forefoot where a chain locker would usually go ..

 

[aerobat]

When it comes to planing out with 5 adults at the stern i think you are just asking your boat to much .

I have seen higher powered 22-25 footers failing to plane out with that load all at the stern .
Every boat has somewhere its limits , its important you know the limits and make best use of the boat inside its limits.

in your case it may be : planing speeds only light loaded , with 5 quests enjoy the cocktail tour .

when memory serves your 170hp rating was written well before this was meant as 170hp at the prop like today,s rating standard.
It is 170hp at the crank , not including the losses at the gearing and - like written above - assuming that every horse is still there in this engine .

That said the b30 is a great engine with a sweet sound and as an inline6 great smoothness.

One more thought, but its only my believe:

Many moons ago a friend had a shetland with a 130hp 2 litre 4 cylinder vp where i wrenched on .

I asked myself how volvo is claiming 130 horses out of a vintage two valve Pushrod ( ohv) 2litre naturally aspirated block !

To push 130 horses out of a non charged two litre you need in automotive applications in any case a modern , high reving fuel injected 16 valve DOHC design .

 

[julians]

I understood your post .. I was just remarking that the drive trim facility is not as VP told me for trimming the drive when in use.

Yes the drive is down at max trim .. I cannot see any way to increase that. I would be extremely reluctant to start adding wedges etc as another suggests.

Raising by one hole ? because of the bigger engine and increased stern draft - its not so easy to get at the pin .. its really a lift out job. Boat will be lifted maybe end of month - so can look then ... but any test will then have to wait till spring.

Drive angle vs water line ? Yes I plan that anyway ..

Attached is the original sales blurb for it ... with sketched line ..
View attachment 200665


OK - just took a couple of photos to show that she really does sit down at stern even when no-one on board.

View attachment 200667

View attachment 200668

I may be wrong - but I believe that the drive should not so buried like that when at rest and no-one on board. That at least a reasonable part of the drive head should be above water ?


OK ... more info :

There is little on board in terms of gear ... the anchor is a 5lb grapnel .. and sits in the locker under cockpit sole. That can go fwd into the bow locker. The behind transom bench backrest - are mooring ropes only. Can always reduce the number or put fwd as well - leaving just a couple in stern.
I have been considering adding a proper stemhead fitting and anchor .. but the boat has no naval pipe or chain locker. I am loathe to start cutting the deck etc. But it can be looked at. Up to now - I have used a small fluke anchor with Ankoralina reel ...
The sales page - you can see thw water tank right in the forefoot where a chain locker would usually go ..

It does look a little low at the stern compared to the drawing in the sales brochure.

Presume there's no water in the bilge/the bilge is totally dry? Sometimes there is a false bottom/floor under the engine, and you can have water trapped under there and not know about it.

 

[Alicatt]

With my small 5.5m dory with a 75hp outboard when we were 6 divers onboard it took a bit of moving people around to get her up on the plane, usually I put the two heaviest guys up front and that got the bow down and lifted the stern, once on the plane than they could come back amidships without knocking us back off the plane.