I installed a 2 blade feathering Variprop and can easily reach over 6 kts at 2400 RPM. This is the RPM that the engine seems to run best at, there is a slight resonating vibration at lower RPMs, this was the same with the fixed 2 blade prop as well.
Cruising speed
- Thread starter Lisa
- Start date
Many here will tell you differently but, as long as you can get the boat insured, having a survey done is ultimately a personal decision. I would heavily recommend a survey to most prospective buyers but in the end it's up to you and your level of risk tolerance.
Full disclosure: When we bought the IP we neither did a survey nor an in the water trial. There were some caveats in the offer covering some obvious stuff, once the boat was launched but that was it. Based on his actions we trusted the previous owner and after plenty of research and going over the boat form bow to stern, felt the boat was solid. (borne out on the trip home from Lake Michigan to Montreal)
The purpose of the thread wasn’t to debate to professionally survey or not. We are well aware of the risks, but are confident that a survey probably wouldn’t reveal much we don’t already know. Most of a survey is visual inspection. Our main risk is not doing a haul out and hull inspection. Gambling that a 10 year old boat doesn’t have any blisters, can’t see a lot of other costly hull repairs. Trusting the owners and age of boat.
The purpose of the thread was to mainly find out what cruising speeds are considered normal and at what rpms, and what temp is the engine running at. Our 27 ran at a cool 160 all the time, so 175 seems warm to us but it seems pretty normal.
The purpose of the thread was to mainly find out what cruising speeds are considered normal and at what rpms, and what temp is the engine running at. Our 27 ran at a cool 160 all the time, so 175 seems warm to us but it seems pretty normal.
>> I was not planning on a professional survey
I thought (I may be mistaken) that some insurance companies won't insure the boat without a professional survey...or am I mis-remembering that detail??
I thought (I may be mistaken) that some insurance companies won't insure the boat without a professional survey...or am I mis-remembering that detail??
My Universal was running around 170 until I took the end caps off the heat exchanger, replaced the gaskets, and cleaned out the zinc remnants sludge that I found there. Once that was done, I dropped down to 160 at 2200 rpms.
Did your 27 have a seawater cooled engine (5411)? Those are designed to run cooler than ones with a heat exchanger, because seawater causes problems at higher temperatures.
I don't remember all the details, but we motor at 5.5-6.5 knots easily. I'm not sure I believe the tach readout-it's on my list of things to check closer. Three blade fixed 15x9 prop. Temperature never gets above 160 (unless I forget to open the thru hull!), but our water temperature is seldom over 60 degrees.
Depending on what instruments are installed, this may, or may not be an issue. There is a calibration screen on most displays these days that allows offsets to compensate for placement or obstructions to be taken into account.
So, if the sensor is reading say, 2kts, and you know for sure that you're going 3kts, you offset the calibration by 1kts and you're close.
It's baffling why somebody would spend the money on toys and then not carry through to getting them working properly.
If the boat has been in the water an not used then your speed will drop due to dirty bottom and prop. I would not finialze the purchase until a haul out was done and inspected but then its your call/money. If you feel that its ok get the bottom done and prop cleaned / painted and 2 new ZINCs installed, you may think this is a over kill but you'll have to haul it out anyway to do the same latter but what you don't want is find that you need a new prop/shaft.
Hi Lisa,
Here is some info from Westerbeke on your engine. With a well maintained cooling system mine runs 160 to 170 constantly. Not much to the cooling system, some easy fixes. Plenty of info here.
I usually cruise at 2250 rpm at around five knots.
Sounds like you just need a good bottom clean and try again.
Good luck, great boat.
Jeff
Here is some info from Westerbeke on your engine. With a well maintained cooling system mine runs 160 to 170 constantly. Not much to the cooling system, some easy fixes. Plenty of info here.
I usually cruise at 2250 rpm at around five knots.
Sounds like you just need a good bottom clean and try again.
Good luck, great boat.
Jeff
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The engine temperature, with everything running properly (i.e., rw pump and HX and hoses) is based on the thermostat. There are two T stats available for M25 and M25XP engines: 160 and 180. Most likely similar if not identical T stats for your M25XPB.
Lots of talk about what cruising rpm people use, but that doesn't seem very helpful. I would find out from engine manufacturer what rpm the engine is supposed to achieve. My new yanmar hits over 3,800 rpm in neutral. I regularly run up to 3,500 to 3,600 under load just to verify that the engine achieves close to max rpm (90% ) just for peace of mind because I am led to believe that if you don't achieve 90% under load, your engine may be losing compression.
So, first I would find out what your target is without load (neutral) and then I would find out if the engine achieves 90% rpm under load (moving thru the water). If it doesn't, then perhaps the prop is wrong, or there is a significant forest growing on the bottom of the boat (not just a few barnacles).
Perhaps I don't know this engine (mine is Yanmar) and perhaps I'm completely off base about everything said above (this is an internet forum and many comments are bound to be completely wrong!), BUT, if I were on that boat and seeing just 2,600 rpm and 4.1 knots on a newish 31' boat with a 26 hp engine, that would be screaming red flags to me. I'm not even thinking about the temperature issue because I think it is just a minor symptom of something more serious. Has this engine lost compression? Are you seeing gray smoke? I have to think that with a clean bottom, a well-maintained engine should run the boat at least 7 knots. I would be appalled by 4 knots, never mind the bottom. You would need a forest growing underneath and an anchor dragging as well to have such poor speed. Something sure sounds wrong with the rpm's to me. If the speed gauge is not lying to you, I don't know how you would want to tolerate such low speed.
I had an engine that did 3,600 rpm in neutral and barely 2,400 rpm under load. While the speed made about 6.3 knots (in fresh water) when the engine was running well at 2,400 rpm, the over-propped engine probably suffered to the point where compression was lost and performance diminished rapidly. I finally was alarmed by gray smoke and blow-by was significant, as the rpm's later topped out at about 2,200 under load (diminished in neutral as well).
If I were you, I would have an engine mechanic get to the bottom of this seemingly very poor performance. An engine re-build would be a very costly mistake for you to address.
So, first I would find out what your target is without load (neutral) and then I would find out if the engine achieves 90% rpm under load (moving thru the water). If it doesn't, then perhaps the prop is wrong, or there is a significant forest growing on the bottom of the boat (not just a few barnacles).
Perhaps I don't know this engine (mine is Yanmar) and perhaps I'm completely off base about everything said above (this is an internet forum and many comments are bound to be completely wrong!), BUT, if I were on that boat and seeing just 2,600 rpm and 4.1 knots on a newish 31' boat with a 26 hp engine, that would be screaming red flags to me. I'm not even thinking about the temperature issue because I think it is just a minor symptom of something more serious. Has this engine lost compression? Are you seeing gray smoke? I have to think that with a clean bottom, a well-maintained engine should run the boat at least 7 knots. I would be appalled by 4 knots, never mind the bottom. You would need a forest growing underneath and an anchor dragging as well to have such poor speed. Something sure sounds wrong with the rpm's to me. If the speed gauge is not lying to you, I don't know how you would want to tolerate such low speed.
I had an engine that did 3,600 rpm in neutral and barely 2,400 rpm under load. While the speed made about 6.3 knots (in fresh water) when the engine was running well at 2,400 rpm, the over-propped engine probably suffered to the point where compression was lost and performance diminished rapidly. I finally was alarmed by gray smoke and blow-by was significant, as the rpm's later topped out at about 2,200 under load (diminished in neutral as well).
If I were you, I would have an engine mechanic get to the bottom of this seemingly very poor performance. An engine re-build would be a very costly mistake for you to address.
I normally haul the boat once a year. The hull is usually quite clean still, but the prop and shaft always foul substantially. The exception was 1 year ago, when the antifouling had been done by some ‘professional’ that obviously wanted to save on antifoul paint – see attached pic.
However, whilst any of those conditions reduced the speed by ½ to1 knt, the engine has never exceeded 160F. It is a 25XPB – some specs say it is 26hp, some say it is 25hp.
I would think that your troubles lie with an engine problem and/or its cooling mechanism. When I bought my boat, sea trials were ok, but when I than took it out on the first outing, I tried to see how much reserve power the engine had and turned it up to 3200 revs. That’s when one of the cooling hoses blew apart and started flooding the boot. It had been blocked by an accumulation of salt, because it had not been used enough. Have replaced all hoses since. My cruising speed is 5.5-6knts at about 80% of max rpm.
Strongly recommend professional surveyor and haul out (if the antifoul layer is too thick and starts peeling off, it may cost you $2-3000 to have it stripped back to bare hull), before buying. The fee of a few hundreds may save you thousands-it did for me.
However, whilst any of those conditions reduced the speed by ½ to1 knt, the engine has never exceeded 160F. It is a 25XPB – some specs say it is 26hp, some say it is 25hp.
I would think that your troubles lie with an engine problem and/or its cooling mechanism. When I bought my boat, sea trials were ok, but when I than took it out on the first outing, I tried to see how much reserve power the engine had and turned it up to 3200 revs. That’s when one of the cooling hoses blew apart and started flooding the boot. It had been blocked by an accumulation of salt, because it had not been used enough. Have replaced all hoses since. My cruising speed is 5.5-6knts at about 80% of max rpm.
Strongly recommend professional surveyor and haul out (if the antifoul layer is too thick and starts peeling off, it may cost you $2-3000 to have it stripped back to bare hull), before buying. The fee of a few hundreds may save you thousands-it did for me.
Attachments
Sorry for the late chiming in but data has been very poor here in St. Thomas as of late.
I suspect you have several issues contributing to what you saw in the sea trial.
First a fouled bottom and prop as has been suggested. Find out what the diver is going to clean and if not too late get him to take pictures or videos of the finished cleaning. Make sure he cleans the thruhull as well. It is small on these boats and easily fouls over time.
Second is water flow. The heat exchanger on the 310 has a zinc. It is supposed to be checked monthly and changed as needed. I bet if you pull it down there is nothing left. And the missing parts could very well be lodged in the tubes of the heat exchanger. Remove the end caps and look for debris. My previous owner bragged about always changing that zinc every year, when I removed the cap I found a stack of broken pieces. If you see debris in the exchanger think about removing it for cleaning and testing at a radiator shop.
Third and keeping with the water flow, check the strainer. There could be stuff that was sucked up in the strainer reducing flow.
Fourth and still on water flow, the impeller for the water pump. The stock water pump, the Sherwood, is a major pain to change the impeller. So I bet it's old and could be tired and warn out. Several of us have switched to the Oberdorfer water pump because it's a better quality and easier to change the impeller.
Fifth fuel flow. Most 310s are equiped with two fuel filters. On engine and a Racor. The on engine is a 2 micron filter. Often I see people running a two micron Racor as well. Check this by throttling up in neutral. You should be able to reach 3200-3600. If it sputters then this could be the issue.
Sixth air flow. The factory air filter is nothing more than a sponge over a metal tube with steal wool in it. Many of us have upgraded to K&M filters that can be cleaned and reused. Look at the air filter, if it's dirty try running without it and see if performance improves. Look at past thread for the K&N filter.
Seventh and final, the exhaust elbow. If the previous owner (I guess current owner) has babied the engine too much then there is likely some carbon build up in the engine. You need to remove the elbow and inspect it with a flash light to tell. You can try to clean it or just make a new one out of threaded pipe like I did.
All of the above seems like a lot. But you could replace all of it for under $2000 if you do the work yourself. None of it is overly complicated or hard. When I look at boats it's nice to have a good engine but it's not the primary thing I look for. You can make the engine situation better for relatively short money in the big picture. But you can't improve hull build quality. You can't typically change the berth configuration. And you can't change that feeling that this is the right boat for you.
Please don't hesitate to contact me if you have any questions. Given our post hurricanes communication issues email is probably the best. Jessek65@gmail.com.
Good luck
I suspect you have several issues contributing to what you saw in the sea trial.
First a fouled bottom and prop as has been suggested. Find out what the diver is going to clean and if not too late get him to take pictures or videos of the finished cleaning. Make sure he cleans the thruhull as well. It is small on these boats and easily fouls over time.
Second is water flow. The heat exchanger on the 310 has a zinc. It is supposed to be checked monthly and changed as needed. I bet if you pull it down there is nothing left. And the missing parts could very well be lodged in the tubes of the heat exchanger. Remove the end caps and look for debris. My previous owner bragged about always changing that zinc every year, when I removed the cap I found a stack of broken pieces. If you see debris in the exchanger think about removing it for cleaning and testing at a radiator shop.
Third and keeping with the water flow, check the strainer. There could be stuff that was sucked up in the strainer reducing flow.
Fourth and still on water flow, the impeller for the water pump. The stock water pump, the Sherwood, is a major pain to change the impeller. So I bet it's old and could be tired and warn out. Several of us have switched to the Oberdorfer water pump because it's a better quality and easier to change the impeller.
Fifth fuel flow. Most 310s are equiped with two fuel filters. On engine and a Racor. The on engine is a 2 micron filter. Often I see people running a two micron Racor as well. Check this by throttling up in neutral. You should be able to reach 3200-3600. If it sputters then this could be the issue.
Sixth air flow. The factory air filter is nothing more than a sponge over a metal tube with steal wool in it. Many of us have upgraded to K&M filters that can be cleaned and reused. Look at the air filter, if it's dirty try running without it and see if performance improves. Look at past thread for the K&N filter.
Seventh and final, the exhaust elbow. If the previous owner (I guess current owner) has babied the engine too much then there is likely some carbon build up in the engine. You need to remove the elbow and inspect it with a flash light to tell. You can try to clean it or just make a new one out of threaded pipe like I did.
All of the above seems like a lot. But you could replace all of it for under $2000 if you do the work yourself. None of it is overly complicated or hard. When I look at boats it's nice to have a good engine but it's not the primary thing I look for. You can make the engine situation better for relatively short money in the big picture. But you can't improve hull build quality. You can't typically change the berth configuration. And you can't change that feeling that this is the right boat for you.
Please don't hesitate to contact me if you have any questions. Given our post hurricanes communication issues email is probably the best. Jessek65@gmail.com.
Good luck
same with mine. I do not think mine will even go up to 3,000 rpms. Maybe my tach reads low.
SimiSAilor posted that chart that indicates wide open throttle should achieve 2900 to 3000 rpm . If your sea trial did 2400 rpm max, that seems to be a problem. The speed also seems to be a problem. Owner represents that the performance is sub-par, so I guess I would make sure Owner fixes problems. If he can't then you are taking a chance on a bad engine. 6 knots max seems like a poor target. Shouldn't that boat get 7 knots with a suitable engine and prop? Not sure why the hull should be limiting potential hull speed. You may not want to cruise at that range, but engine performance is important, no?
I wouldn't look at the operating temp as a problem. It may be a symptom of a problem. Not sure where normal cruising ranges are relevant. Low cruising ranges shouldn't be an excuse for tolerating poor engine performance, which may be expensive to fix if it has more to do with the engine than the barnacles and forest growing on the hull.
I wouldn't look at the operating temp as a problem. It may be a symptom of a problem. Not sure where normal cruising ranges are relevant. Low cruising ranges shouldn't be an excuse for tolerating poor engine performance, which may be expensive to fix if it has more to do with the engine than the barnacles and forest growing on the hull.
Diver reported running gear was in desperate need of cleaning. Cleaned prop and shaft and added a new zinc. Reported hull was clean with only a few barnacles and they came off easily.
Second sea trial is Saturday. Thanks for all the conversation, I will let you all know how it goes.
Second sea trial is Saturday. Thanks for all the conversation, I will let you all know how it goes.
Again a key test is what can you get pushing the throttle all the way forward in neutral. I did mine today and hit 3200 rpm max. Please report back on the sea trial