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Discussion Starter · #1 · (Edited)
I'm looking at a Bristol 29.9 this Friday. The ad says it has a Yanmar YB12 single cylinder 10hp engine. The age is the same as the boat, so it must be original.

The Boat US review says these boats were made with an Atomic 4 at first, then a 15hp Yanmar, then a 16hp Universal.

Is it likely that the owner and broker are wrong?

I'll know in a few days, but I'm just curious if anyone can confirm the stock diesel in a 1977 B29.9 (I think it is the 2QM15, but I might be confused with another boat). I can't find a reference for a Yanmar YB12, only a YSM-8 & a YSM-12.

It looks like a decent boat at a good price:

1977 Bristol 29.9 Sail Boat For Sale - www.yachtworld.com

...but a 10hp engine (even a diesel) isn't gonna move it very quickly.

Ken
 

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Discussion Starter · #3 ·
Thanks, Barq.

I found site with the info from the original sales brochure and it also said 'Yanmar 15hp diesel'.

So, in 1977 (according to the site you linked to) that must have been a 2QM15 (raw water cooled).

I guess I'll know soon enough.

Ken
 

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Discussion Starter · #4 ·
I found my notes from a B29.9 I looked at last year; it had the 2QM15, from the factory, in 1979. So that where I got that idea.

While we're on the subject, how can a 15hp diesel take over for a 30hp Atomic 4?

Do diesel engines deliver their power at a lower rpm?
 

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Atomic 4 owners rarely get 30 HP out of their engines; more like 10 - 20 HP under normal usage.
The Beta "drop in" A4 replacements come in a range of horsepower ratings from, say 12, 18 & 24HP.
 

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Brokers frequently get these details wrong - I'd do some checking. But it does look like the stock engine should be a Yamaha 2QM15.

I'd be rather cautious about a 35 year old, raw water cooled engine. It could easily be on its very last legs.
 

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Pretty boat! (I may be biased).

The original owner of my boat ordered it with an engine upgrade to the Yanmar 2QM20. I've not heard of a B29.9 fitted with a single cyl yanmar but I dont see why not, I imagine that there were options at the time.

But does seem that the 2QM15 was std equipment: Bristol 29.9

I dont think you'll have trouble pushing it with a 10 or 12 hp diesel, with the proper prop. My previous boat (2000lbs lighter) had an 8hp yanmar and did just fine. Having a few extra horses is noticeable but I would not consider it a deal breaker.

 

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It might also be that the broker is using the std HP one can use ALL the time, ie 12HP, and the 15 hp is the 30 min max useage. I'm recalling my 85 2gm18 is 18 all the time, up to 20 intermittent in its rpm useage.

A motor that size will move your boat. but if it gets rough, fast current etc.....you may be slowing down some. My 7K boat does that with a 2blade prop! A 3 would be better.....

Marty
 

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Discussion Starter · #11 ·
Thanks, guys!

I didn't know that the A4 came in different hp ratings; everyone just says "Atomic 4" never "12hp Atomic 4". Then again my hearing is shot...

There were no pics of the engine in the listing, not a good sign.
 

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I'm looking at a Bristol 29.9 this Friday. The ad says it has a Yanmar YB12 single cylinder 10hp engine. The age is the same as the boat, so it must be original.

The Boat US review says these boats were made with an Atomic 4 at first, then a 15hp Yanmar, then a 16hp Universal.

Is it likely that the owner and broker are wrong?

I'll know in a few days, but I'm just curious if anyone can confirm the stock diesel in a 1977 B29.9 (I think it is the 2QM15, but I might be confused with another boat). I can't find a reference for a Yanmar YB12, only a YSM-8 & a YSM-12.

PS she does look like a nice boat!

It looks like a decent boat at a good price:

1977 Bristol 29.9 Sail Boat For Sale - www.yachtworld.com

...but a 10hp engine (even a diesel) isn't gonna move it very quickly.

Ken
Yes, diesel do put out more horse power at lower RPMs.

Thanks, guys!

I didn't know that the A4 came in different hp ratings; everyone just says "Atomic 4" never "12hp Atomic 4". Then again my hearing is shot...

There were no pics of the engine in the listing, not a good sign.
Well the A4 is "rated at 30 HP" but you have to rev it very high to get that. Most people seem to have them propped to have much lower RPM as the motor is happier at that range. Gas engines seem much happier at lower power output. The diesels need to have a "load" on them and are happiest at the max HP output so people prop them to be at the peak HP as that is max efficiency. So it is not an apples to apples comparison.
 

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I may be a little late to this party of be of help, but here's two comments.

My previous boat was a Cal 9.2 (30 foot) and the 11hp Universal 5411 pushed it just fine.

The issue with the Atomic 4 is that most are direct drive (no reduction in forward). This means a small fine pitched inefficient prop and the engine is never loaded up to anything close to the rated 30 hp. A 10 or 15 hp diesel with a 2/1 or higher reduction gear and larger prop will produce more thrust than the A4.
 

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Discussion Starter · #16 ·
So what did you think of that boat? How many horsepower did it actually have?
I can't find the picture I took, but it was a very small diesel; not the QM15 (which I had seen pics of before).

As much as I wanted to like it, the boat was just 'ok'.

The deck had been painted and was peeling everywhere.

The price to replace the original underpowered diesel was US$7,500 (15hp) or $9,800 (21hp) for just the engine. Add to that haul, store, install labor, and launch ($3k? $4k?); there was no way that it was happening.

I found another B29.9 in Tiverton, RI that we both like better; we close this Friday. :D
 

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I have a 1978 29.9 #94 with a standard Yanmar 2QM15 raw water cooled. Pushes the boat to hull speed easily with some available "emergency power" using a three blade prop. As I understand it Bristol would equip the boat with what was available that the purchaser wanted at the time.
 

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I have the original 2QM15 in my 1980 Hunter 30 and it's still going strong. Grranted the boat spent its first 20 years in fresh water (great lakes). Aside from normal maintenance, I have repaired the fuel pump and replaced the mixing elbow.
 

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Hopefully you've found the boat for you in Tiverton; the B 29.9 is a great boat and FWIW mine is an early 1979 and has a QM 20 which I assume was an original upgrade, RWC and seemingly in fine shape after a brief 35 years. I replaced the cracked exhaust mixer last year but otherwise the engine, other than being just a bit cranky to start in cool weather, is, uh, "Bristol". Good luck to you with your purchase.
John
 

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I may be late to the conversation, but for what it's worth: We're on our second season with a 1979 B 29.9 and we are thoroughly happy with the boat. We sail in Casco Bay in Maine. 'Velella' has the original Yanmar 2QM15, that you mentioned. This seems to be a good size for the boat. We easily motor at 5 knots, at about 2000 rpms.

But I don't think that 20hp would be too much in this boat. Based on that, and in light of the fact that Bristol later included a 20hp model, 10hp might feel 'light', especially if you will be sailing in areas with strong tides or currents.
I suggest test-steaming the boat under power to make sure that you will be comfortable poking along for hours in nasty conditions.
 
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