Bertram 25 express repower

[Howesounder]

I have been playing around with the express with its 25" 3100 hour Yamaha 250 four stroke for a couple months now. Getting 38 knots with a 17" prop with the engine at 6200 rpm. Very high speed performance is good, but the 25" engine is just too short and the prop is ventilating in anything over very moderate sea conditions, and more so at lower speeds. I have also found that in steep wind over current seas, the boat and operator take a real thrashing at the 20-26 knots that one would like to charge through at, but the boat is constantly falling off, and having power added to get back on plane when trying to dial in a slower, but not plodding speed in that rough stuff. So I made a huge 32" wide X 18" planing plate like a huge oversized commercially available hydrofoil. Even with this too short leg, the boat will now plane solidly at 11 knots, but the slightly improved ventilation is still an issue when it's snotty out.

I found an extra long leg Mercury 150 four stroke in stock locally due to a deal gone sour, so a pretty good price. (5K less than the Yamaha 150 extra long leg) Then I did some reading on the Merc, and I kind of liked what I read, so I bought the dam thing.

Kind of expecting to get a beating here (thank you in advance:) over the idea of such puny power for this boat, but I loose 200 lbs, with this swap, and Merc has a 16" diameter, 14" pitch prop that I think will be perfect for the 12-22 knots I want this boat do cruise at. Hp curve of the 250 sort of suggests that at my 20 knot rpm I am only using 95 HP. I will use the oversized planing plate on the new engine. My calculations tell me that wide open the boat will do 28-30, down from 38 knots with the 250. 3000 rpm should then give me about 14-15 knots with the planing plate on, so 4500 rpm should be 21-22 knots. 20 knots at 4250? I pick up the engine next week, and will start rigging soon after, so will report back as soon as I am back on the water with the real world results.

Happy boating all. Steve

[Carl]

Who's gonna be beating ya?

...your boat, you do what you want, you cruise how fast you want.

Personally, I think boating should be fun and enjoyable, I like the ride, its part of the enjoyment.
I am not sure what the sense of getting someplace super fast is (offshore fishing grounds somewhat excluded), especially if you, the boat and your crew are beat up on arrival.

As to whether its a good choice or not to stick that chunk of aluminum off the back of your boat...beats me.
All I know about outboards is they go outside the back of the boat and I like the smell of the two cycle ones...reminds me of my yut (my cousin Vinny)

So good luck with the new purchase!
Carl

[Howesounder]

I meant the most welcome and friendly man cave type ribbing really. This boats last owner had 550 two stroke hp strapped on, so yes....whatever floats your boat for sure. I too love the smell of two stroke oil in the morning, but the four strokes just run so well.

As far as the chunk of aluminum, it's a miracle worker for this boat in regard to low speed performance. I have a 14 foot four winns fling that I converted from 120 hp jet, to a 25 hp four stroke tohatsu outboard. (You can see this low hp thing is a trend) it scoots along at 21 knots wide open. It was a bear to get plane with two adults, and would fall of plane very easy. Would not plane with three adults. Added a Davis plate to the outboard and now it planes easily with three adults aboard.

I have purchased a bobs machine shop jacking plate for it, and am building two aluminum receivers to be bolted to each the side of the boat about 1/3rd from the front. Then will mount a pair of dol fin outboard foils on a pice of flat bar, and have them one at the bottom and a second about 4-6 inches higher. These will mount into the receivers, and stick down about 18-24 inches below the boat. Give er the gas, have it rise up on the foils, then lower the outboard to "raise the back of the boat as well on the Davis plate. Trim to keep it riding right with the tilt after that. This for use when it's choppy out I use the boat to commute each week to a summer cabin, but when it's rough things get very slow, hoping this convertible hydrofoil will smooth things out when it's choppy. Idea of staggering the height of the foils is to have only as much foil in the water as required at given speeds, if the boat leans one way by a of much, the second, higher, foil will create lift.

[Tony Meola]

I have to agree with Carl. Each boat meets ones individuals needs.

Just have fun.

[Navatech]

Your boat, your dough, your idea of fun...

Knock yourself out whichever way suits YOU best...

[Carl]

I meant the most welcome and friendly man cave type ribbing really.

If you want ribbing...I can do that too.

Why hang a chuck of aluminum a foot over the water that will corrode the crap out of it...stick a real inboard motor in there...make it a diesel too for extra torque and economy.
A 25 hp Tohatsu...crap man, what the hell are you thinking! My boats blenders got more push then that little egg beater. You should be ashamed of yourself and banned from this forum for even saying something like that!

Guys, members of the Faithful! Can we get a poll started to vote this Aluminum Hangen' EggBeater Loving excuse of a boater out of our Sandbox!


Howesounder,
Hows that? too much ribbing?

I too love the smell of two stroke oil in the morning, but the four strokes just run so well.

The 4 strokes do...but the two stroke smell brings back memories of some great times.

[mike ohlstein]

I keep some Castrol bean oil handy. A couple of drops in the gas tank of the snow blower, ATV, chain saw. mmmmmmmm

https://www.amazon.com/Klotz-BC-172-Rac ... B000WPUVVQ

[captbone]

Congrats on your purchase. I look forward to hearing the performance results.

I would recommend the Enertia 16 x 13 pitch prop to start.

I would expect top speed near 35mph.

[Howesounder]

Went to pick up the engine today, and measured before we loaded. Engine is a 25 inch, they don't make a 30 in the 150. Happy I checked though! The fellow at this place thought the XL was 30" back to the drawing board.

Steve

[Eagles 17]

Steve
thats too bad about the engine.
I was dropping off my daughter inlaw off at langdale terminal that has to be your boat anchored
there boat looks good.
Hope you come across another engine that fits your needs.
Bill

[Howesounder]

Bay manufacturing make a 5" extension for the 150 Merc that converts it to a 30" checking to see if that voids my warrantee.

Played around with some numbers today with a great tool from Victoria propeller. Used their calculator and the specs from the b25 express, and used the single 250 hp Yamaha presently on the boat. It came up with 38 knots as a top speed using a very reasonable 170 constant in the formula. (My test ride gave me 38 knots) I then dropped the weight the 200 lbs I expect to loose with the 150 hp Mercury four stroke, and got a new expected top speed of 30.5 knots. Since I hope to cruise at 20 knots, or .666 of that top speed, I would hope to be doing 20 knots at about .666 of 6000 rpm or just under 4000 rpm

So going to pull the trigger on that Merc after all, unless they would void warrantee on me.

[Eagles 17]

20 knots is a real comfortable speed in our local waters.
Good luck with Mercury.

[Howesounder]

Finally got the Merc 150 and 5" leg extension on this weekend and took it out for trials. Leg now might be a bit low in the water, but it's close. (Quite a bit of spray from the leg) I put the 32" wide planing plate on the lower fin of the 5" extension so it's only in the water at lower speeds. (So not on the engine cav plate) after a few hours of putzing around I gave it a quick stab at full throttle and got 27 knots, and over 6000 rpm so not quite enough prop, but the boat is light now, so I will leave this 14" pitch, X 16 diameter prop on. Back to 19 knots and the engine is really relaxed......21 knots and you can hear the vacuum dropping, and the engine starting to work. Looks like 4200 rpm gets me 19 knots, so a success. Boat sits quite a bit higher out of the water now with the 200 lb less engine. Rear corners are just out of the water at rest. No ventilation problems at all, even over big ferry waves, and hard corners etc. Engine is quiet and smooth.

Steve

[captbone]

Great news!! An Express Bertram 25ft with a single 150hp 4 cylinder outboard hitting 31mph and still being underpropped with a 20mph cruise.

Please post some pictures.

[Howesounder]

Thanks for that Captbone, I will get some pictures up here soon of the boat at speed. I have had a chance to put some hours on the boat with the Merc 150 now. Looks like the engine is now a little too deep in the water as there is quite a bit of spray from the engine. Spray goes away when I trim up, but the boat slows down when I trim up enough to clean up the wake. I will raise the engine by one hole soon. I did 45 nautical miles this weekend doing 18.5 knots on average, and burned 75 litres, or 17.5 imperial gallons. (I think the American gallon is 4/5th of an imperial gallon) I have a hunch that the economy will get a bit better without the rooster tails, but as it sits I am paying about 2 bucks per N.M. Might seem a bit high to many of you, as I suspect you are paying quite a bit lees for fuel? 4000 rpm is netting 18.5 knots.

Steve

[Eagles 17]

Steve
Your boat looks good.
Bill

[Carl]

Gotta love it when a plan comes together...
Did your homework and got the results you where after, has to feel terrific!
Enjoy and best of luck with it!
Carl

[TailhookTom]

Carl:

As a member of the deplorable and despicable teams -- why not take a chainsaw to the transom and cut a nice healthy notch out of it to lower down the 250 to it's proper resting place?

As far as setting your boat up the way you want -- I'm a big supporter -- hell, I had VOLVO diesels in my Bertram 31 AND I have Yamahas on the back of my Pursuit and these guys still talk to me in here, but my dues are really steep now!

Good luck with the boat and the repower!

Tom

[Tony Meola]

Carl:

As a member of the deplorable and despicable teams -- why not take a chainsaw to the transom and cut a nice healthy notch out of it to lower down the 250 to it's proper resting place?

As far as setting your boat up the way you want -- I'm a big supporter -- hell, I had VOLVO diesels in my Bertram 31 AND I have Yamahas on the back of my Pursuit and these guys still talk to me in here, but my dues are really steep now!

Good luck with the boat and the repower!

Tom

Tom

We just feel sorry for you since you own a Pursuit.

[Howesounder]

Got my permanent tach the other day and scrapped the beat up one that came with the boat. Values between the two tach were pretty far off. Turns out that with the 3x16x14 pitch prop the boat was actually doing nearly 7000 rpm at wide open throttle. (Yikes!) I double checked with our non contact digital and this new tach is the correct one. Thankfully I spent only 30 seconds at wide open, a few times. Curious that the rev limiter did cut in a couple times but only when I was at wide open, and I lifted the engine too high trimming up. Hate to think where that limiter was cutting in. Chucked on a 4 blade 15 3/4" diameter 15" pitch prop I had kicking around from the Yamaha 250, and that dropped wide open to 6400, still 400 above redline. Speed was 32 knots. 20 knots was 4800rpm. 4600 gives 18.5, and I think I will stick with this prop. By the time I get the boat loaded with a few people and the gear it will have on board once complete, I think the top end will be back at 29-30 knots and 6000 rpm with this prop.

Playing with those numbers, if 6400 gives me 32 knots, that's 1 knot per 200 rpm. So 20 knots should be 4000 rpm, not 4800. I suppose as the boat goes slower, more boat, and more leg is in the water, and that is what y'all have been pointing out to me about these hulls being more efficient at above 22 knots? Might be even more the case with this outboard/pod version as only when you get above 22 (ish) knots, does the wake stay flat behind the boat long enough to keep much of the leg out of the water (30"leg) When going slower, the water, 3-4 feet behind the boat has risen up and is keeping much of the leg in the stream, and that's why I have the big spray wake at below 22 knots. Food for thought. A jack plate would allow me to raise the engine a bit for my 18-20 knot speed......ad weight and complication. A stainless steel V shaped non adjustable trim tab the same angle as the hull........about 3 feet wide, and tapering back to a point about 1 foot wide about 2 feet long would give the hul a bit more lift, and prevent the water from risking up and flooding the leg at my desired cruise. Sort of trick the boat into thinking and acting like a 27 foot boat, and push the centre of weight forward a bit to make up for the outboard and bracket hanging way back there?

Steve

[CamB25]

What does your boat weigh loaded and ready for adventure? Too much weight, too little push. Does she ever get over the hump and plane?

[Howesounder]

Not sure of the weight Cam. Stock boat, but even with the pod, and single 150, I suspect it should be lighter than it was with a pair of 4, or 6 cyl I-Os I have only about 200 -250 lbs of stuff to add. Water is full, tanks are full. With this huge hydrofoil I put on the outboard, it's on a healthy plane at 14 knots, and the wake cleans up pretty good even at 11. Top speed today was 32 knots, cruising along nicely with the engine feeling very relaxed at 18.5 The foil is completely clear of the water by about 22 knots.

Steve

[CamB25]

Well then I'm confused. I thought you had a big rooster tail and wave behind the boat at22 knots...like you are plowinf the sea running bow high and not on top of the water.

[Howesounder]

Still working the kinks out Cam, yes the wake is pretty clumsy looking when the boat starts to plane. Gets better and better as speed goes up. I call being on plane, whenever you see black water, all the way along the back of the boat, no boiling etc. That starts at 9 knots now with this monster 32" wide whale tail installed on the outboard. Then as above, quite a bit better at 11 knots, and a very no "bs" plane at 14 knots. So by 20 knots this spray goes away if I tilt up enough, but that in turn slows the boat down, from 20 to 18, as the bow is just too high. At higher speeds the spray goes away completely even at the best trim, as the water has not had enough time at this speed to rise up, (wake really flattening out) and so its correctly rushing past just the lower part of the leg. I suspect that the leg with its 5" extension is now a bit too low, and if I raise it 1.5 inches, or one hole on the backing plate, I won't have to tilt up as much, to eliminate the spray, even at lower speeds,(hopefully as low as 16 knots, as the leg will be that critical amount higher. So Yes to get rid of the rooster at lower speeds it's bow high now, because to get the leg out of the water enough to stop the spray, it is tilted up too much. For now I trim for the best speed, and ignore the silly looking wake. Will raise the engine first, see if that helps, and expect it will help. If it doesn't, or the engine ends up being too high and ventilating the prop, I will put that hull extension, non adjustable tab I described above to allow the back and bottom of the boat to be closer to the outboard leg, and therefore allow the engine to act like it is much closer to the transom, and therefor not have all that water blasting the upper leg at lower speeds.

Steve

[bigshrimpin]

Steve - Thanks for posting the numbers and details of your repower. This report helped me solidify the decision to go with a 150 merc.

[Howesounder]

You are most welcome. I just love the leverage we are able to give each other in this site. The Merc continues to perform well. Not sure what you are mounting it on, but if it's a 25 Bertram, and a single, then a leg extension kit will be required. Also keep in mind this 150 would not be nearly as satisfactory without that 32" wide hydrofoil I had wayerjet cut. If this engine pod was of the type that extends down, and increases the wateerline length, I don't think I would have needed that foil

Steve

[bigshrimpin]

Hi Steve - I appreciate the advice. I'm familiar with the bay MFG kits.

Some folks have called me nuts to put a single 150 on the back of a 23 seacraft. Between your report, the sailfish 22 bulletin (4450lbs) hitting 38mph turning a rev4 bulldozer prop ( http://sailfishboats.com/wp-content/upl ... letins.pdf ) and 5 years of running a 30+ year old 175 2.4L merc on the boat (42 - 43mph top end) . . . I'm making the leap. Thanks for posting the numbers.

Tim

[Waytooslow]

Steve it definitely doing some R&D on his boat on the power side. I think it is a great exercise to try various options and I commend him for his efforts. I probably fall in to the more traditional camp of wanting to go with adequate power on my B-25. Captain Bone’s experiment proved that a single 250 HP was adequate. I run a single 250hp on a jack plate on a 21’ center console currently and it really is adequate power but not crazy overkill on that boat. I have not yet settled on a power choice for my boat but I will probably want at least 300HP so I may have to go with a couple of used 150's or 200’s as being a more affordable option. Todd

[Howesounder]

Your guys all live in a world of less expensive gas than us up here above the 49th. I would love to storm along at 30 knots when the conditions allow it but I am too cheap. My fuel consumption doubles to go from 20 to 30 knots, and of course the speed has not doubled. I just can't get my head wrapped around the extra cost. The compromise I made on HP was not the only one. I really would have liked a pair of engines, but my research sort of indicted at least a 15% drop in fuel economy penalty for having that second leg in the water. So I have to have a high thrust 10 HP clamped to the pod, and this only gives me 5.5 knots in an emergency. Also acts as a small generator if I ever run the batteries down, and can't get the main started.

This boat did 45 knots with 450 hp, 38 knots with 300, and 32 with 150. From 300 hp to 150 and only an extra 6 knots. 300 to 450 and only 7 knots more. I think according to the HP curve, I am drawing 100 hp at 22 knots, and we know it takes 450hp to do 45 knots, so to double my speed I have had to use 4 times the HP! I get a bit of a chuckle seeing how little engine I can get away with. When I had only a little 12 foot aluminum boat, I tried a 2 hp Honda on it with a tiller extension. That boat would get up and plane, do 14 mph with me and one of my kids on board. Me on the middle seat. my next experiment with this Bertram will be to build down from my pod with styrofoam sm to mimic the hull bottom. I wonder if I can do away with this huge hydrofoil on the outboard if I increase the waterline length by the length of the pod. Should move the centre of weight a bit forward to make up for that engine and pod cantilevered out there.

Steve

[bigshrimpin]

Steve - Did the dealer say anything about the warranty after installing the 5" bay mfg kit?

[Howesounder]

Hello Big Shrimp, I have no faith in this particular dealer. Kind of a boutique lake based wake boat selling outfit that has very little to do with outboards. Kept me waiting weeks for cables.....I said "but ther are just bla bla cables".......standard as pacific time, they insisted NO, these are a new cable, not to be confused with that standard I specified. Said none were available for 6 weeks. I went to a real dealer nearby, he told be where six pairs of the yes, standard cables were, and I could have them the same day. Wakkeboard outfit told me that the engine was 30 inch.........Merc don't even do a 30" in this engine. So on the warrantee......they fudged, and it sounded to me like they did not even ask Mercury. ..........."we don't think it will be a problem if the warrantee problem is not caused by the extensuion" So I am sort of just taking my chances on this, as no one makes a 30" from the factory in this HP range. I had a 150 hp Suzuki forstroke on my centre consul, but Bay don't do a kit for Suzuki. Yamaha was the "sure bet" but I sort of liked what I was reading on the Merc, even though mercury has never been my go to brand. One thing I could have done without on the Merc is this "smart start" You just touch the key, and the "smart start" ends the crank cycle. Engine goes through a couple seconds of cranking and starts. My Suzuki was analog.....starter stays in only as long as you are in "start position" on the key. The Suzuki was running in micro seconds........I would often joke that it would start if you even looked at the key to hard.

Steve

[bigshrimpin]

Thanks Again !!!!

[captbone]

Great news. I am very excited to see a 23ft Seacraft with a single 150hp Mercury I4.

15 pitch Enertia prop to start?

I expect 37-38mph and 3.5mpg at cruise. Please keep us posted.

[bigshrimpin]

Sorry for Hijacking this thread. I'll start a new thread on CSC when I get it mounted and rigged.

Capt Bone - Will do . . . I have a 15 Pitch Enertia on the way.

[Howesounder]

Have fun, hijack away......you are gonna love this engine!

Steve

[bigshrimpin]

Steve - Thanks again for all the information. I mounted the engine last week and just finished the break in period. It'll tickle 40mph down wind.

[Raybo Marine NY]

I keep some Castrol bean oil handy. A couple of drops in the gas tank of the snow blower, ATV, chain saw. mmmmmmmm

https://www.amazon.com/Klotz-BC-172-Rac ... B000WPUVVQ

I also use this oil,but be careful it seperates from the fuel when it gets cold ,think its 35 degrees.
I only use it in the warmer months