Improving access

Improving Access to the Rear of the Engine

John Nixon, Orta Vez; Hull #728, c34hull728@gmail.comrsen, C34 Association Technical Editor

In this issue we have a nice article directed at those folks who have abused (or contemplated abusing) themselves trying to work on or around the rear of the engine in our pre-Mk 2 boats. The author is Dave Spencer who lives in Southern Ontario with his wife, Kathy. They enjoy sailing their 1994 C34 Mk 1.5 on the Great Lakes; mainly Georgian Bay and The North Channel.


–John Nixon, Orta Vez; Hull #728,


Current Access to the Engine 


Access to the rear of the M35AC engine for routine inspection and prudent maintenance on my 1994 Mk 1.5 C34 named Good Idea has always been difficult. I sought wisdom from the helpful crowd on the C34 forum and learned that newer Mk II C34s have cabinetry panels that can be removed to gain access to the rear of the engine but the enclosure separating the aft cabin from the engine compartment on my boat is fixed fibreglass cored with plywood. After years of awkward access, it was time for some alterations to create an opening that would become my maintenance access hatch.


Hatch Selection


The group on the C34 forum offered three suggestions for a hatch on the rear engine wall:


Custom made, off the shelf or home-made teak door similar to those that provide access on the port and starboard side of the engine, A panel secured by cleats or grooved battens, An off the shelf hinged marine hatch


Since my cabinet making skills and my budget couldn’t accommodate a fancy teak hatch and the aft cabin is rarely occupied by discerning teak aficionados, I elected to go with a premade marine hatch. I picked up an A Marine-made watertight deck hatch (AMRE1-243-607-01) from Amazon for about $45 CAD (on 12/2018 about $47 USD on Amazon Prime). This hatch requires a 525 x 168mm (20 5/8" x 6 5/8") cut-out. The outside dimensions are 607 x 243mm (23 7/8" x 9 9/16") giving me a nice big flange for a neat appearance (and to hide any cutting errors). I had initially selected a smaller hatch but the group on the C34 forum correctly recommended getting the biggest hatch that would fit. I was pleased with the robust and neatly finished product when it arrived.


Preparation Work


I carefully examined the inside of the engine compartment to ensure there would be nothing in the way while cutting the rear wall. I had several fuel and water hoses that I had to cut free from their tiedown cleats on the rear wall and I carefully tied them back to the engine to ensure they wouldn’t be damaged by drill bits and jigsaw blades that were soon to invade their previous home. I made a cardboard template of the cut-out and positioned it about the centreline of the engine. I was briefly concerned that the very solid 20 mm thick rear wall of the enclosure was so robust that it must have some structural purpose. However, the enclosure clearly doesn’t support any other part of the boat and I was satisfied that the wall was designed heavy to reduce noise, vibration and, to a lesser extent, heat emanating from the engine.




Before cutting, I drilled a couple of small (1/8") probe holes along my cutting line to see where the cut would end up in the engine compartment. Satisfied that I had drawn the cut-out in the right place, I drilled a couple of larger holes to allow me to start cutting with the jigsaw. The combination of fibreglass and plywood was tough to cut and my blades, designed to cut wood, quickly became dull. I clearly had the wrong blades for the job but I was 250 km from home and the excellent local hardware store was uncharacteristically bereft of carbide jigsaw blades that day. I persevered with what I had and was eventually able to claim success… a bit prematurely. When I trial fit the hatch in the hole, I found the hole was about 1 – 2 mm too small in a few places. After some dusty work with the barrel sander on my drill, the hatch slipped into place.


Hatch Installation


Before installing the hatch, I lined it with acoustic / thermal insulation similar to the material used in other areas of the engine compartment and sealed it with a layer of aluminum tape. I elected to install the hatch with the hinge at the top thinking that it would swing up above the mattress in the aft cabin and leave an unobstructed surface to lean on while working in the engine compartment. However, I found the hatch would only open about 170 degrees as it hit the teak fiddle on the shelf above before it fully opened to 180 degrees. The open hatch significantly obstructed my view looking down into the engine compartment and it would have been really no better if it opened the full 180 degrees. I removed the hatch and rotated it to hinge at the bottom, drilled pilot holes and secured it in place with 3/4" #6 flathead screws. This greatly improved the view into the engine compartment; especially the view of the transmission dipstick which is notorious for being difficult to see and difficult to reach.


With improved access to the rear of the engine, re-securing the hoses that I had pulled away from the wall was a relatively easy task.


After One Season 


I’m very pleased with this improvement. Checking and changing the transmission fluid is now an easy task that I used to dread (and therefore didn’t do as often). The hatch provides excellent access to the heat exchanger zinc, the heat exchanger and associated hoses as well as the electric fuel pump and the exhaust elbow flange. I wish I had thought to do this job a few years ago when I removed the heat exchanger and replaced all of the cooling hoses. Replacing the failed electric fuel pump two years ago would have been much easier too.


The pictures are taken with the mattress removed. With the mattress and bedding in place, I need to compress the mattress slightly to allow the hatch to open. This is not any inconvenience and it’s an easy trade-off to get the access I now have to the rear of the engine. With the hinge at the bottom, I thought the open hatch would obstruct my reach into the engine compartment but it doesn’t. I leave the mattress in place when I check the transmission fluid but I protect it or fold it out of the way if I have any messier jobs to do.

–Dave Spencer, Good Idea, Hull #1279,

Plus, discover more articles in the Spring 2019 issue!