Transom Height / Extension

[Raymond]

Wanted.

I need to extend a transom that is at proper height for a Y302 in order to accommodate a Y102. If you have such a set up I would appreciate it if you would post some pics to help guide our design.

Yes! I am outwardly asking to steel your speed secrets; don’t tell anyone.

[Raymond]

What are your thoughts on this design

We want to mount a Y102 on a transom setup for a Y302 and need to come up an inch to an inch and a half and we don’t want the clamp screws to close to the edge of the transom. What are your thoughts on this design? Does it need a cap such that it should be one peice design in the shape of inverted U?

[sam]

Don't forget the plates will be very slippery to the clamps which are designed to grip wood

[bill van steenwyk]

another option

Raymond:

Why don't you lose the doubler piece and just go with the thickness you need to build the transom up as you have shown, and attach it to the existing boat transom with four pieces of 3/4" or 1" aluminum angle, two each side, with one bolt thru each side of the "build up piece" front to back on top and then maybe two bolts equal distance apart top to bottom thru the transom itself for a total of six bolts. Lightweight and easily removed by just taking out the bolts that go thru the angle pieces and the transom. Have used something like this numerous times in the past on both runabouts and hydros when changing motors with differing tower housing lengths and never had any problems with it staying in place. If you are concerned about strength you can still go with a couple of long screws or lag bolts vertically down into the transom but I never found it necessary and I used this method for 4 cyl Mercs.

ADD: As per Sam's point, if you use this method you still clamp right to the original transom and the amount of weight added to the boat is very small, just the block on top the transom, four pieces of aluminum angle and the bolts.

[seanp3]

Raymond

I've actually used your design and worked well. You will be adding very close to 1" in height for the Y102. Without having a plate the transom clamps will be right at the top of the transom where you're adding the extension. I would want to make sure you have something solid to clamp to. The extra alluminum doesn't really add that much weight.

[blueskyracer]

We want to mount a Y102 on a transom setup for a Y302 and need to come up an inch to an inch and a half and we don’t want the clamp screws to close to the edge of the transom. What are your thoughts on this design? Does it need a cap such that it should be one peice design in the shape of inverted U?

[ATTACH]25091[/ATTACH]

I have done two boats just the way you have it drawn and have had no problems and the motor clamps have never slipped but then I use a cheater pipe to make sure they are good and tight

[ZUL8TR]

transom increase

We want to mount a Y102 on a transom setup for a Y302 and need to come up an inch to an inch and a half and we don’t want the clamp screws to close to the edge of the transom. What are your thoughts on this design? Does it need a cap such that it should be one peice design in the shape of inverted U?

[ATTACH]25091[/ATTACH]

Your sketch is fine. Here are some suggestions. Go with 3/16" alum plate for stiffness. I would use plated hanger bolts 1/4" x 20 x length to suit (not avail in SS) at the transom bottom inside and out and cut vertical slots in the alum to accept bolts. Also could use the same hanger bolts instead of the screws at the top and countersink for the securing nut and washer. This eliminates the complete removal of the screws. This way you only have to loosen the 4 bottom nuts and the 2 top nuts to vertically lift out the height increaser. Make the increaser wide enough and position hanger bolts such that they are clear of the engine brackets and allow rev sticks to easily be R&R with 302 engine in place.

Check and see if your Yamato clamps have worn washers that are causing the clamp stud to push past the circular clamps when tightened and the stud would bore a hole in the transom. My Y80 does that and rather than fix the worn washers I added alum to the transom and cut 2" +/- x 3/8" wide slots in the aluminum to allow the stud to pass. This setup also allows for quick centering of the engine and a means to restrain the motor if it tries to lift off. You can still use the cheater bar that Blueskyracer notes.

[johnsonm50]

We want to mount a Y102 on a transom setup for a Y302 and need to come up an inch to an inch and a half and we don’t want the clamp screws to close to the edge of the transom. What are your thoughts on this design? Does it need a cap such that it should be one peice design in the shape of inverted U?

[ATTACH]25091[/ATTACH]

Ive extended several transome as you show with no problems.. be sure its tight & on clean bare aluminum.