bertram31.com

In looking through some past topics I have seen where it is not recommended to exceed 320 HP because at 29 knots the run angle becomes to flat without prop pockets, and the nose will dive.

I think most 31's with 315 yanmars hit 32 knots WOT. If you install a 370B (355 bhp) in a bahia mar with a marlin tower I think it would hit about 34 knots on the pins.

What I would want is more HP than I can use so the load on the engine is less. Basically, prop a 370 to 3,100 and cruise @ 2,600. This ought to be around 27 knots. Can a 31 be run at 27-28 knots without the running angle becoming a problem.

Thanks,

Sam

I'm sure you'll get a lot of opinions but mine is that a diesel SHOULD be run at it's proper cruising rpm for the long term health of the engine. Unlike gas engines where longevity is extended by running well below it's WOT, diesels running at 200 below WOT lubricate properly and can go forever. The other end of the coin is, properly propped, you'll be causing a wake going through your marina at it's slowest unless you put in trolling gears.

Walter,

I don't think the 200rpms of the top belief is accurate for all applications. I know the common thought on my 300hp 6BTA's is to prop them to 2900rpms at WOT and cruise at or below 2400rpms. I think it all depends what engines you're running.

I have the yanmar 315s and run 27-28 knots all day in my Bahia Mar. I burn 10 gal a side at cruise. I have saddle tanks and a lot of ice [1700lbs]. I dont know if more hp is really needed.

dougl33 wrote:Walter, I don't think the 200 rpms of the top belief is accurate for all applications. I know the common thought on my 300hp 6BTA's is to prop them to 2900rpms at WOT and cruise at or below 2400rpms. I think it all depends what engines you're running.

10% off the top.......

Not for the Cummins 330Bs.

What I would want is more HP than I can use so the load on the engine is less

The idea of over powering the boat to ease the load on the engines and thus giving longevity is fruitless.

You run into issues with larger hp engines in the 31 and turning the proper diameter/pitch props and not being able to fit them below without the use of prop pockets, extreme pitch or 2 speed gear boxes all of which is a waste on the 31.

A proper set up 31 doesn't have a speed problem persay. Only when it noses over does the bow V act like a rudder and you can't steer the boat.

Large pitch wheels can make the ass end climb up lowering the bow creating this effect.

A set of properly sized Cummins or Yanmars will outlive any owner with proper care.

A 330B with a 1.5 gear propped to 2,900 will turn a 20x24x4 with a med cup.

A 370B with a 1.5 gear propped to 3,100 will turn a 20x23x4 with a med cup.

Some people like the 370 vs. the 330 because you develop the hp a little higher up the rpm curve. More oil and coolant flow, raw water flow, and piston cooling.

Bruce, you are correct, a set of yanmar or cummins set up right with propper care will probably outlive the owner. The wear difference between the 330 & 370 is probably minimal.

I guess what I need to know then is 20x23-24x4 is not too much pitch, and at 27-28 knots, the bow shouldn't nose over?

Thanks,

Sam

sam i have no idea where you read those awful rumors but you should just dispel them as pure nonsense.the 31 bert will run at a perfect plane angle at 37knots you just have to follow a simple line of though.pretend our forefathers knew what they were doing in the height of sailboat shipping in the 1860era.they use ballast in the very bottom of the ships or they concentrated the heavier cargo in the bottom of the hold on centerline.----ok present day; water tank,batterys,fuel, all along centerline of keel.engines as low and as far back as possible.i have 2006 cummins on dyno a real 314 hp at shaft. listed as 330hp. here we are at 32 knots sleeping at the wheel.

Bob,

Beautiful boat. What brand and length of outriggers do you have. I have the Lee Wishbone mounts, but need to buy new poles. I was thinking about going with the 22' Lee's. I like the clean look of the way you have yours mounted.

John

they are rupp 22' poles.

and the bases are 7' tournament by rupp.

Hey...I know where that picture was taken....nice shot

year brother you were there, i am only sorry i did not have a drink with one of the best.this year we will have to make up for my short stay.were ever this years bertrams brother meet i will be there.

Bob, you do have an exceptionally nice looking B31. Great shot.

SPrater,
There's a guy named Moffet...I forget his first name, but, he lives in Freeport Tx a mile or so from me. Anyway, he owns a flybridge with full tower powered by 370's. Boats name is "Bullet". From what I hear, she'll haul ass with no dipping in the bow. I talked with one of his buddies last year and he said that they ran 80 miles offshore at 35 knots the whole way out and back again. I'll be in Freeport this weekend and will get his number if you want. Might want to talk to someone who has what you're looking for.I'll be on a boat most of the weekend, so call me at 713-906-0842 if interested.

Anyway, he owns a flybridge with full tower powered by 370's. Boats name is "Bullet"

That would be the good lookin blue and white flybridge in the listings on this site:
http://www.bertram31.com/listings/moffat.htm

Thanks John, I saw that blue 31 at a boat show a few years ago. My family has a house in Rockport. I appreciate the information. Did you go with 315 yanmars on your bahia mar?

Sam

gentlemen thank you for the compliments on my boat.i just wanted to say a cummins 330b and 370b are EXACTLY the same engine and same part numbers except fuel injection pump and ratings.i have a set of 370hp pumps and in one day can convert (along with props) to a 37knot cruise but your forgetting one major drawback. the can go no slower than 12knots causing a hell of a problem is you come to a 5mph zone prior to docking in your marina and let me add this --thats one hell of a wake you are not going to make friends and you have to back into a slip at 12knots in a wind you could have a bad day!!! the only remedy is mention by bruce a zf-down angle,two speed trans. very expensive and brewster can verify you really can`t do more then 28knots to the canyon .usually there is waves kicking up on that 100 mile run to big eye territory. not to change the subject but i always wonder why a bertram like" bullet "used offshore does will a bow rail or a bow pulpit??? here in the north we have a basket with 800' or more of line and anchor connected to a retrivel ball .we put the hold thing under the hatch in the cockpit and just throw the anchor in the water from the cockpit then turn boat around and give a pull and make sure she`s set opon retrival connect line to cleat run forward as you curl the rope into the basket and the anchor pops up in the ball .just pull the ball to the boat and put it away.i just don`t understand the concept of standind on the bow in raging seas trying to lift anchor or worst yet trying to stuff all that line in a anchor locker with a filthy anchor if you tell me you hang the anchor on the bow --------thats the worst possible situation you could do to a bertram. you complain about possible nosing in -think what your doing this is not a aircrafy carrier you are thowing the entire balance with all that shit on the bow!!!!

Jeeeez Capt. Bob... there is more than one way to do things ya know.
But, I don't see any evidence of a roller on Bullet's bow...
Maybe Mr. Moffat simply likes the way the updated bowrail and pulpit look... and in the event that someone does have to go up there in any kind of conditions, it sure adds a helluva safety measure. I know I've had to shimmy my way out on the bow of a smaller Merritt, and a few other custom SF with no rail, in prime sailfish conditions (N winds at 20 to 25mph) and I would've given my left nut for a sturdy bowrail everytime...
Yep, I like the clean look without the rail better... And the anchoring method you describe is how most guys down here do it as well, but there could be things you're not taking into consideration.
Just sayin.

For me a bow rail is a MUST. It may have something to do with the wave period in the Gulf vs the Northeast. Our very short wave periods down here jerk and throw the boats around volently. Down here a 3-5ft sea will keep most at home.

I could be off base on the "why" of a rail, but I couldn't image a boat without one. The foredeck without a rail seems like a really dangerous place to be. Plus the weather and water are warm, so spray & getting wet is no big deal, we get out on the bow frequently for numerous reasons. Pulpits are great for sight casting along weed lines as well.

It would seem that the risk are greater up north (because of dangerous water temp) and everyone up there would want a bow rail?...unless you guys just don't get out on the foredeck?

Dunno, but that is an interesting observation Bob.

buju you make a point just did not know if the retrival ball is a northern thing and now you answer that (well in the keys anyway). buju in my experiance i seen noting but problems with the bow pulpit,winch,rollars. you no the look of those blubliners coming into the marina with the sad face and 100' of line on the deck with a jamed winch. they sure do put a load on the battery as well as screwing up one way or another.what about the foot switch standing on the bow taking up line know you really need that bow rail .i imagine if you were in the carribean the situation would be differant but even then in deep water thats a hell of a pull with a rode of 7 times the depth on a electric motor

scot never been on the bow offshore .i sight from the bridge with binoculars. like i said our application to fishing may be differant than yours. personaly never had faith in a windlass . maybe to drop the hook in the bay if i was a disable person. but to carry that weight in the extreme bow and limited room in the rope locker. how could i possibly put enough chain on the line to hold in that depth and stuff it all into the rope locker???i have a alluminum fortress anchor in the rope locker with 100' of line as a backup and to drop in 10' of water in the bay for winter flounder while chumming but is rare.

In the PNW it is common to see pulpits with high bow rails. The whole area is basically one huge archipelago and not very well charted. I often see wise skippers moving slowly with someone on the bow watching for submerged rocks, of which there are many. Not so often, I see skippers blithely zipping by. That's when I get in the boat and go pull someone off...

sounds erie like moby dick in the fog. or early american explorers -----"land hoe"in the fog.

Sam, I am building a 66 Bahia Mar w/370 Cummins, ZF 1.5-1 220 Down angle gears with trolling valves, 1/3/4 shafts, plan on putting a full tower on as well. I have carefully listened to Bob Licos advice on weight placement. I moved the engines back about 4", slid the fuel tank back as well, made all new bulkheads, retabbed the entire boat, heavy duty custom engine mounts and got the weight as low as I could. Flattened the shaft angle to 13 1/2 degrees....Overbuilding everything as I go...Brewster how many gallons do you carry? Main, saddles?

smart move putting in the trolling valves right off the bat.i had nobody to guide me with my setup ( every bit of weight shifted to aff of rear bulkhead) i experimented until i got it right.i had three sets of engines in the same boat so i can tell first hand the differance in plane angle,handling,tenderness in rolling seas,time to plane,ability to take head sea`s,backing down.did you go with pss packless shaft seals,and kevlar shaftlog?? that boat should cruise around 32knt but best fuel economy may dictate around 29kns.

Sam,
I just got back from Freeport, and, yes, I went with the lp 315's with ZF 220a's with 1.5 ratio...will see what she'll do in a few months. I'm with Scott on the bow rail issue. Bob, here in Tx, most of us anchor up like you do, but the bow rail works well when casting on a weedline or snapper/ a.j./ warsaw fishing close to an offshore plattform. We pull into my boat slips bow first, and its a piece of cake getting off of the boat with a bottle of Fire Fly vodka in tow. There's several bars in our area, and the rail makes things alot easier, as far as docking or having something to hang onto for hopping on or off of the boat.

Having that bow rail is like having a fire extinguisher in your house (tip of the hat to Andre). When, not if, you do need to go up on the bow it may save your life.
At least you'll look sharp falling off that nice open bow with no rail.

Bob H I have one saddle in front of each engine. They are 55 gals each. The main tank is 180gals. I have no gen. between the engines is a fish hold and between the saddles is another fish hold. I removed the water tank so that whole compartment is ice and fish. I also had Dave Wessler build me a custom bow rail that is overbuilt. That way a big guy can hold on to it in big waves and it does not move at all.

Brewster said:

between the engines is a fish hold and between the saddles is another fish hold.

A floating meat locker, we would expect nothing less from you Brewster!

love you guys i learn something everyday. i can`t imagine docking a 31bertram bow first .i guess it doesn`t bother you backing out of a slip?
on the subject are you allowed to hook up to a oil rig or is there a distants you must be off of it??

Bob,
Alot of my neighbors have blown out their bulkheads by washing them out with the prop wash. I guess by pulling them in bow first, it keeps the props away from the bulkhead...i don't know if it's something to do with our Tx mud, but it works. I don't know of anyone out here who has been ticketed from hooking up to a rig, but, some of the rigs are unmanned and nobody seems to care. Sometimes on the rigs that are in production and are manned, the rig operator will ask you to unhook so that a crew boat can pull up and do their thing.

We all carry rig hooks. 50 ft of rope with an aluminum hook on the end, an elastomer in the line helps. We bow first up to the rig, throw the hook and hang off the down current side. The hooks have a release tag line that flips the hook off when your ready to go. Snagging a horizonal member on the first shot is an art form.

As John noted, many (if not most) of the production platforms are unmanned. With over 3,000 platforms in the Gulf it would be tough to police! I have never been ask to leave, they will often come down and tell you if they have been catching fish.

Neebie don't do....DON"T tie up to the smaller remote flare platform!!! lol.