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Outboard set up advice and next steps

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    Posted: 22 Nov 2020 at 10:40pm
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Righto before throwing money around guessing what’s the best option i am seeing some advice from you knowledgeable forum members.

Background, current boat is a 2004 Ramco renegade 620.

Upon purchase was powered by a 200hp v6 2 stroke mercury. Motor was fitted with outboard fins. Weight Aldine 185kg.

Motor ran great and boat performed well however drank like a fish so 2 years ago repowered with a new Honda bf150. The motor is outstanding however I don’t believe the ride has even been as good as before and seems to have a few issues. Weight around the 230kg mark.

1. Porpoising at high speed with any chop with engine trimmed fully down. Most of the time Infact I hardly can use much trim only ever operating on 1/4 range on the gauge.

I just want to be able to get the nose down more. When loaded with a fully chilly bin on front of cabin the boat performs much much better.


Outboard is currently as high as it can go however on the plane and trimmed up the cavitation place is still sitting under water and not visible so a bit unsure what’s the next course of action to try fine tune a bit better.

These are my options and interested in your thoughts on any or a combination of a few.

1. Install 5 degree wedges to add
More trim range.

2. Install hydrofoil fins, bit worried with this as cav plate currently sits below waterline.

3. Install trim tabs. ( much more expensive option).

4. Change prop? Current prop is currently performing well in other areas.

Cheers in advance

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Post Options Post Options   Likes (0) Likes(0)   Quote pjc Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 5:33am
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extra 45kg hanging on the transom so have tried placing 45kg in the bow to counter weight the extra weight??
Cannot see hydros helping while plate is under water.
Have you seeked advice from Ramco??

I read that it preforms better with bin up the bow ,maybe the easy the option ballast??
How does it tow with the new motor?
Don't come home without fish,wonder what the lawns look like??
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 9:17am
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Got to this and straight away thought  "engine height"
And possible high rake ( Mercury Raker) prop.

 1st concern you have is the extra 45kg on the transom.
 Yes at anchor the boat will sit a little lower in the water, but once you get over the bow wave up on the plane .. and think about that.. that the hull skimming across the water surface..And coming out at the keel height behind in an elipical curve to the rear...
Thats all good.. no problems here.. you are on the plane.
 But your issue is the cavitation plate is not at the level of that epiltacal curve out the rear....
And that is the problem..
 the 45kg weight is now irreverent, the engine is  low.

1. Porpoising at high speed with any chop with engine trimmed fully down. Most of the time Infact I hardly can use much trim only ever operating on 1/4 range on the gauge.

 A drop of that much in HP (%)  at the prop is huge, and so will the hull performance. Thu with correct engine height and propping, fuel and hull performance would improve hugely.

 Adding perm trims etc are for under powered. @ 150hp 4S maybe getting to min power (??)
What was the WoT speed at normal boat load with the old engine?
Having the engine low, even say 1 notch down will add, in effect a good 150+ kg to the boat... 180 to 200 easy. Thats a lot of performance and fuel.

2nd what prop do you have on the bottom?

1. Install 5 degree wedges to add
More trim range.

 This will not do anymore than what you are doing with the trim ATM.
 Its is not the problem.

2. Install hydrofoil fins, bit worried with this as cav plate currently sits below waterline.

 yes will lift the stern.. it also has more drag, more gas than should use, thu will be better than now. End of the day it is not the problem, it is a poor patch, at best a chinese sticking plaster on a wound that needs stitches.

3. Install trim tabs. ( much more expensive option).

Yes will help, but again it is a patch fix, it is not the problem.

4. Change prop? Current prop is currently performing well in other areas.
 
Covered above comments. Props are used to fine tune performance ONCE everything else is installed correctly. Not the other way around.
Propping is done in this order... and only in this order
1. engine height
2. slip (correct grip/ diameter)
3. Then pitch.

Outboard is currently as high as it can go however on the plane and trimmed up the cavitation place is still sitting under water and not visible so a bit unsure what’s the next course of action to try fine tune a bit better.


This is the problem that needs to be fixed.. not patch fixed.

Soln is increase the mounting height.
If mounting bolt holes are too close to the top, and cant re drill, soln will be a jack plate.
Going jack plate, do not just bolt a fixed on on.. You need to also allow for the extra distance from the bottom of the keel, and the extra height because of that distance with the elliptical curve height of how the water surface comes out from under the keel.

 I very strongly suspect from this comment

Motor (the old 200hp 2S) ran great and boat performed well however drank like a fish

That the engine height on that was also low, assume same engine leg  length (??) .....ineffect a good 150/200 extra weight on the boat, and that 'weight' gets greater the faster the boat goes.
And it still performed well otherwise because of the extra reserve power behind the 200 hp.
 Now dropped hp, you dont have the same reserve power to 'cover over ' that extra in effect weight of cavitation plate low.

I hope I have explained well enough that you understand what is going on here.


 
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Post Options Post Options   Likes (1) Likes(1)   Quote MATTOO Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 5:20pm
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My two cents.

We all expect boats to preform properly out of the gate.

Unfortunately they don't. And there is a stack of reasons.

Some hull shapes just don't ride well, you can trim and balance for Africa . The manufacturers sometimes build dogs.
However some dogs can be improved in performance but not completely solved.

In your situation you identified one area that many overlook.
, is balancing the boat.
Like any craft, vehicle. Balance of the item is crucial.

I suggest first up use your gear as value weight items for performance.
The influence is relevant.
Start there.

All boats and there gear should be balanced.for the performance factor.of any given machine.
Just cruising in my now sweetas pimped out Southern 755 HT0!
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Post Options Post Options   Likes (0) Likes(0)   Quote DIY Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 6:26pm
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Is it possible that it’s a long shaft motor when it should have been a short shaft? Sounds like even raised as high as possible it’s still too deep. If the motor ends up needing to be higher, could you get a fabricator to raise the transom. Just a thought.
Oh what a smasher - two eggs and a rasher!
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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 7:49pm
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Originally posted by pjc pjc wrote:

extra 45kg hanging on the transom so have tried placing 45kg in the bow to counter weight the extra weight??
Cannot see hydros helping while plate is under water.
Have you seeked advice from Ramco??

I read that it preforms better with bin up the bow ,maybe the easy the option ballast??
How does it tow with the new motor?


No haven’t tried any extra weight up in the bow only the chilly bin forward outside cabin vs at back of boat and definitely rides better, his would be 100kg when full of fish approximately.

Don’t bother trying Ramco anymore as have tried in the past and this is a new lot of owners with a new lot of hulls and to be fair weren’t very interested.

Upgraded trailer same time as the outboard and it tows mint never had any issue there.
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Post Options Post Options   Likes (1) Likes(1)   Quote RC1 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 7:55pm
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Steps you are 100% correct so no need to add my cents worth here.
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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 8:07pm
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Originally posted by MATTOO MATTOO wrote:

My two cents.

We all expect boats to preform properly out of the gate.

Unfortunately they don't. And there is a stack of reasons.

Some hull shapes just don't ride well, you can trim and balance for Africa . The manufacturers sometimes build dogs.
However some dogs can be improved in performance but not completely solved.

In your situation you identified one area that many overlook.
, is balancing the boat.
Like any craft, vehicle. Balance of the item is crucial.

I suggest first up use your gear as value weight items for performance.
The influence is relevant.
Start there.

All boats and there gear should be balanced.for the performance factor.of any given machine.


Ye cheers haven’t done much before moving weight but will definitely do that for now, it’s not terrible but I know it can be better.

Here is the boat for reference, it already has a large bow with good size cabin so possibly always trying to get more weight forward could help.

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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 8:11pm
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Originally posted by DIY DIY wrote:

Is it possible that it’s a long shaft motor when it should have been a short shaft? Sounds like even raised as high as possible it’s still too deep. If the motor ends up needing to be higher, could you get a fabricator to raise the transom. Just a thought.


Old motor was a Mercury XL which is 25” I believe and was installed from new so assuming this one is also a 25” if on highest hole and still needs to come up a bit.

For reference here is a photo of the leg.

No video but waterline sits half way between cav plate and next Ridge up. From factory install I had one hole to play with which I moved up but now am maxed out.

Could get outboard pod raised but probably the most painful option in terms of ease.

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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 8:26pm
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Originally posted by Steps Steps wrote:

Got to this and straight away thought  "engine height"
And possible high rake ( Mercury Raker) prop.

 1st concern you have is the extra 45kg on the transom.
 Yes at anchor the boat will sit a little lower in the water, but once you get over the bow wave up on the plane .. and think about that.. that the hull skimming across the water surface..And coming out at the keel height behind in an elipical curve to the rear...
Thats all good.. no problems here.. you are on the plane.
 But your issue is the cavitation plate is not at the level of that epiltacal curve out the rear....
And that is the problem..
 the 45kg weight is now irreverent, the engine is  low.

1. Porpoising at high speed with any chop with engine trimmed fully
down. Most of the time Infact I hardly can use much trim only ever
operating on 1/4 range on the gauge.

 A drop of that much in HP (%)  at the prop is huge, and so will the hull performance. Thu with correct engine height and propping, fuel and hull performance would improve hugely.

 Adding perm trims etc are for under powered. @ 150hp 4S maybe getting to min power (??)
What was the WoT speed at normal boat load with the old engine?
Having the engine low, even say 1 notch down will add, in effect a good 150+ kg to the boat... 180 to 200 easy. Thats a lot of performance and fuel.

2nd what prop do you have on the bottom?

1. Install 5 degree wedges to add
More trim range.

 This will not do anymore than what you are doing with the trim ATM.
 Its is not the problem.

2. Install hydrofoil fins, bit worried with this as cav plate currently sits below waterline.

 yes will lift the stern.. it also has more drag, more gas than should use, thu will be better than now. End of the day it is not the problem, it is a poor patch, at best a chinese sticking plaster on a wound that needs stitches.

3. Install trim tabs. ( much more expensive option).

Yes will help, but again it is a patch fix, it is not the problem.

4. Change prop? Current prop is currently performing well in other areas.
 
Covered above comments. Props are used to fine tune performance ONCE everything else is installed correctly. Not the other way around.
Propping is done in this order... and only in this order
1. engine height
2. slip (correct grip/ diameter)
3. Then pitch.

Outboard is currently as high as it can go however on the plane and
trimmed up the cavitation place is still sitting under water and not
visible so a bit unsure what’s the next course of action to try fine
tune a bit better.


This is the problem that needs to be fixed.. not patch fixed.

Soln is increase the mounting height.
If mounting bolt holes are too close to the top, and cant re drill, soln will be a jack plate.
Going jack plate, do not just bolt a fixed on on.. You need to also allow for the extra distance from the bottom of the keel, and the extra height because of that distance with the elliptical curve height of how the water surface comes out from under the keel.

 I very strongly suspect from this comment

Motor (the old 200hp 2S) ran great and boat performed well however drank like a fish

That the engine height on that was also low, assume same engine leg  length (??) .....ineffect a good 150/200 extra weight on the boat, and that 'weight' gets greater the faster the boat goes.
And it still performed well otherwise because of the extra reserve power behind the 200 hp.
 Now dropped hp, you dont have the same reserve power to 'cover over ' that extra in effect weight of cavitation plate low.

I hope I have explained well enough that you understand what is going on here.


 


Hi Steps, thanks for the comments, old outboard top end was about 42. knots. Current outboard is 35 knots.

Here is a photo of the current prop. Even with the drag this Honda is ridiculous on fuel consumption even though sounds like it could be better.

Haven’t checked if redrilling mounting holes is a option as this could be a easy solution!

Understand a few of the Options are patches however for now a cheaper patch would do me fine as don’t want any major headaches like transom height extension and welding work ect. Bit a slight improvement would be good.

Used the boat for 2 years On the west coast and goes fine but I know it could be a bit better but it’s whether the effort required is worth the outcome.


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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 8:32pm
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Steps Hull is rated to 175hp max so I’d say the Honda would be mid range in the outboard power size.

Cruises around 4400rpm doing 26 knots and consuming 24lph.

Drop back to 4100rpm and cruises 20 knots and consumes 18lph.

Trolling at 6.5 knots doing 2100rpm consumes 6.2LPH.

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Post Options Post Options   Likes (0) Likes(0)   Quote Kandrew Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 8:48pm
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Doesn’t really seem to make a lot of sense, what does the cav plate line up with the bottom of the like.

If both motors are xl shouldn’t be a problem, I would think it’s more to do with the angle of the pod

Just re-read your post you said the 2s was fitted with fins, do you mean a hydrofoil. Can you run a straight edge out from the bottom of the hull and then measure up to the mounting holes, I think your boat was built for a standard motor not an xl.
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Post Options Post Options   Likes (0) Likes(0)   Quote Dunwurkn Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov 2020 at 9:10pm
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Originally posted by Kandrew Kandrew wrote:

Doesn’t really seem to make a lot of sense, what does the cav plate line up with the bottom of the like.

If both motors are xl shouldn’t be a problem, I would think it’s more to do with the angle of the pod

Just re-read your post you said the 2s was fitted with fins, do you mean a hydrofoil. Can you run a straight edge out from the bottom of the hull and then measure up to the mounting holes, I think your boat was built for a standard motor not an xl.


No a bit odd, owner prior to me bought brand new from Ramco through fish city so pretty sure it would be fitted with correct outboard height and then likely replicated with new outboard.

A 20” would sit the power head much lower to the water it wouldn’t be good.

Yea old outboard had a se sports 300 hydrofoil fitted.

Outboard is on a pod but I will run a straight edge on it when I’m next at the boat.

Possibly I should try trimming out a bit more when cruising and check cav plate level again to ensure it is showing below the water. There wasn’t much on it last Time I checked but thought it looked under.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Nov 2020 at 10:35am
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Hi Steps, thanks for the comments, old outboard top end was about 42. knots. Current outboard is 35 knots

 Old engine 200hp 2S 43kn (48.3mph)  approx 1630kg 
(1600/1800 is where I would guesstimate gross weight on water would be)
New 175hp 4S 2080kg (45kg of that is new motor)
 So a net 400kg  increase in weight...

Cruises around 4400rpm doing 26 knots (30mph)
16" pitch
Gearbox 1.87:1 (please confirm?)

15.8% slip thats Surprising very good.. considering engine fitted to low and get prop diameter right ..either they knew engine was low, got right, or didnt know Assumed correct for correct hight, and got it horribly  wrong for that.

Drop back to 4100rpm and cruises 20 knots (23 mph)
(mphs.. the app I made to do all this is in old school mph because was far easier to do the coding that way)

Thats 30.8%.. my 1st thought here is one of these bits of data is wrong. Assuming the 1st is correct then 4100 would be about 27mph
Or was the trim was not adjusted for each speed


Trolling at 6.5 knots doing 2100rpm consumes 6.2LPH.

Trolling.. now this is a TOTALLY different kettle of fish.
You are now displacement/ semi displacement hull where rather than engine size, and hull length become the critical factors and not gross weight on the plane.
 Ideally, one would use 1 prop to get out there, and then do a prop swap to a mutiblade larger prop to troll.
 Down side in practice, try to get any hull performance with that prop is fruitless. Get a marlin on the try chase down..fuel gauge drops like a lead sinker and lots rpms and no speed.
 I have actually done this exercise on a 'fish for a feed' trip on a prop I picked up a few months back...just to see what happens, rather than just  theory.

 From Kandrew:
Just re-read your post you said the 2s was fitted with fins, do you mean a hydrofoil. Can you run a straight edge out from the bottom of the hull and then measure up to the mounting holes, I think your boat was built for a standard motor not an xl.

Also measure the distance from the back edge of the keel to the front (closest to the stern) edge of the engine leg

 If the engine was mounted direct on the transom, we would be looking at the top edge ventilation plate to be slightly to about 3/4" above. Since its out on a pod, anything from 1 to 2".. as a ball park initial install starting point.

Possibly I should try trimming out a bit more when cruising and check cav plate level again to ensure it is showing below the water. There wasn’t much on it last Time I checked but thought it looked under.

Get upto just below normal cruise speed on flat water with trim lower than should be for that speed.
Now increase trim height till the bow just starts to porpoise and/ or the engine just starts to ventilate.
Now get someone to wave their cell phone around the engine to catch some good pics if the caviation plate.
 Also note rpms and speed.


last Time I checked but thought it looked under. 

Now we are west coast, in practice I have found in smaller hulls, 5.5/ 6m , the cavation plate is best slightly lower than east coast. And I mean  1/2 to 1" . Which means you could end up like us East coast a smidgen high, drop a notch for west and now a smidgen low..

Haven’t checked if redrilling mounting holes is a option as this could be a easy solution!

 Check how close you can go to the top edge on the pod.. do you homework here. A normal transom is 3/4"

Understand a few of the Options are patches however for now a cheaper patch would do me fine as don’t want any major headaches like transom height extension and welding work ect. Bit a slight improvement would be good

End of the day the simple patch fix..
 Say a permtrim.. there goes any warranties, you dont end up with things going as well as the could, including fuel.
Trim Tabs: there is the expense, the fitting, the drag  and again still use more fuel than should, possibly more.
 Jack plate: maybe, Easy install, will put the engine out another 1 or 2" which may create a little more ventilation than if mounted direct to pod..And they are around $700.
Get pod modified: The correct fix.
 Think about it.. engine come off, 30 mins 2ppl, tops. Hardest part doing at home is a engine hoist and harder, a trolly to put engine on.
Tow boat to a engineering workshop , its not a big job, most likely cheaper than any others except a bloody permatrim.
Re mount engine...30 mins
 Think about it..
 But lets get a bit more info, etc before going off 1/2 cocked.

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