2006 Hunter 25 - Swim Platform Stress Cracks

[Ralph Johnstone]

Almost forgot we were waiting for these pictures.

Two more items:

- Do you trailer the boat with the engine on the transom ?
- Could you number the photos (lower corner) as it becomes difficult to discuss photos with so many presented as evidence ?

At first glance, the photo with the callout "motor mount stress cracks" does not cover enough of the interior of the transom to offer any real support for the motor mount. There will be some prep work and cleanup, but what you're finally after is, rather than two narrow sticks acting as backing you want two large area plates in the same location. The trick here will be to ensure that in between the plate and the transom is a spongy fiberglass cloth that will take up all imperfections in the transom. There is some question about composition so the larger the area the better. My lack of knowledge of cloth weights speaks for itself.

Perhaps another method is to fill the gap between plates and transom with Bondo. Maybe others have used this and can speak for its resilience around water.

This is a start and we can move on from there after you come up with a solution for this first area.

 

[Ralph Johnstone]

Arghhhhhh !

These last pictures are a horror story with nut tightened against FG with washers only for backing. These are more difficult to back up but it must be done.

Also, I'm afraid that trailering the boat with the motor on the transom (also not tied up as per @Crazy Dave Condon) is what's caused your current batch of problems. Now that the damage has been done and the structure weakened, you may not be able to tow the boat with the motor on the transom even after repairs. Maybe with great amounts of muscle backing you may be able to tow again but only with the motor properly supported. One would have to be there to evaluate.

 

[Crazy Dave Condon]

@Ralph Johnstone

there are many issues but the engine will need to come off before being trailered. Also issue of backing plates as well. I will respond then

 

[robm]

@Crazy Dave Condon and @Ralph Johnstone,

Thanks for the initial responses; will respond to your requests for info, photos, photo markup numbering, etc. after I drive over to take additional photos, and check the rudder mount. Until then, read on for some responses and additional thoughts I've had since I discovered the cracks.

I. Outboard Motor / Transom / Transport

• Concur that removing the motor when trailering is warranted going forward until:
  • Transom / swim platform is repaired and reinforced.
  • Motor support is implemened (transom saver or equivalent).
• If the above is still too risky, removing the motor during transport is feasible given how we use the boat:
  • Move to summer location at start of season.
  • Launch / recover from boat ramp located 50-100 feet from the trailer location throughout summer.
  • Move boat to winter location at season end).
• I'm thinking that a transom saver would be a good thing to use 100% of the time the motor is attached to the transom while the boat is on the trailer, even when it's at its summer location.

II. DIY Fix Options

• Motor Mount: Reinforce interior transom with G10 backing plates fastented to transom interior fiberglass surfaces using a proper adhesive.
  • Jamestown Distributors has 12" x 12" x 1/4" G10 panels in stock. They also have larger 1/2" panels, but yikes they are expensive.
  • Was thinking the right adhesive to use would be a thickened epoxy like six10 or equivalent.
  • After installing the above, use the existing motor mount holes as guides to drill through the G10 plates, and then through-bolt the motor mount.
  • Note: The above would require the removal of the existing interior backing plates, assuming they are surface-mounted (they appear to be).
• Rudder Mount: TBD; I need to get a closer look and shoot more photos. That said, if it is washers on fiberglass, then at a minimum, I'd think about doing the following:
  • Remove the rudder + mount.
  • Clean up / remove existing backing material (if it exists).
  • Add layers of G10 backing plates + thickened epoxy.
  • Drill through the G10 backing plates using the rudder mount as a guide.
  • Reinstall rudder mount using longer bolts.

III. Transom Rebuild vs. Alternative Propulsion Options

If a proper repair to the transom requires paying a boatyard to reconstruct it, I imagine this could run into thousands of dollars. If that is accurate, then I am wondering if a combination of DIY fix + going with an alternative propulsion option is worth considering.

• Option A: Torqeedo Cruise Electric Outboard. I have an older Torqeedo Cruise 2.0 that I could try using instead of the Tohatsu 9.8. It's rated for up to 6000lbs displacement, and it would be relatively easy to do the swap (I have enough batteries for a trial).
  • Weight: 35 lbs vs. 82 lbs for Tohatsu 9.8.
  • Center of mass is closer to transom.
  • Trivial to remove for transport.
  • One issue: it's no longer repairable per Torqeedo, and I am waiting to hear back from their support people about the risk of water intrusion past seals that are no longer available.
• Option B: Torqeedo Cruise Pod Electric "Inboard" Option (AKA Go Big or Go Home Option). Torqeedo now makes a couple of Cruise Pod models that would allow us to move the motor from the transom to a pod that is just aft of the keel on our H25.
  • Pod drives - Electric, for sailboats and motor boats
  • This would not be a trivial change, and it remains to be determined if it's even possible to make this work on an H25.
  • That said, if if it is feasible, this is a significant upgrade beyond removing stress from the damaged transom.
    • It would free up the swim platform for dinghy use (not davits; just thinking about transferring people/cargo while anchored).
    • It should theoretically provide more effcient / consistent propulsion by reducing cavitation.
    • It's an electric drive, which is environmentally friendly, quieter, and requires less maintenance.

Appreciate any feedback anyone has about the above. To be continued later today or tomorrow morning

Thanks again for your time!

Rob

 

[Crazy Dave Condon]

Don’t do anything till we talk. What is your phone number. Hunter warranty called me for advice and had me involved on the east coast from Georgia to New York when others did not know how to repair. You have several things going on at one time. By the way at least one of the pedestal bolts are leaking.

 

[Ralph Johnstone]

I like your ideas for the transom reinforcement. Epoxy is the best (and most $$$) but you can prep the surfaces and let them thicken a bit before pressing the G10 into place and bolting it gently to begin with and then increase the force as the epoxy sets. Makes for 100% fused area. Much better that FG which suddenly gels and that's all she wrote.

 

[robm]

- Could you number the photos (lower corner) as it becomes difficult to discuss photos with so many presented as evidence ?

Done. All but two now have sequential numbers in the lower right corner; the other two are numbered, but in the lower left and upper left due to existing caption constraints.

At first glance, the photo with the callout "motor mount stress cracks" does not cover enough of the interior of the transom to offer any real support for the motor mount. There will be some prep work and cleanup, but what you're finally after is, rather than two narrow sticks acting as backing you want two large area plates in the same location. The trick here will be to ensure that in between the plate and the transom is a spongy fiberglass cloth that will take up all imperfections in the transom. There is some question about composition so the larger the area the better. My lack of knowledge of cloth weights speaks for itself.

Concur. I measured the area yesterday, and it looks like I can fit up to two 12x12x1/4 G10 plates under the transom from the starboard side of the transom to the starboard side of the rudder mount hump. Another alternative would be to replace the narrow strips with 6x12x1/4 G10 plates if that would be enough to stop the flexing.

Perhaps another method is to fill the gap between plates and transom with Bondo. Maybe others have used this and can speak for its resilience around water.

Bondo probably isn't the right choice here; I seem to recall that it isn't waterproof, but I get what you're looking for re: leveling the surface for a backing plate. As noted in a later comment, I was originally thinking of thickened epoxy, but your mention of Bondo made me think about something like 4200 or 5200, depending on the desired level of commitment to this repair. Note: thickended epoxy + G10 plates is a solid commitment, of course.

One thing that could be a challenge: getting the plates to be level relative to the top of the swim platform. Am unsure how precise this needs to be, but if the angles differ, the nuts and washers for the motor mount bolts would not be flush/level with the G10 plate.

This is a start and we can move on from there after you come up with a solution for this first area.

Agreed. The motor mount is the most critical issue to resolve, first, unless we decide to go with a transom rebuild / reinforcement by a pro to address all of the issues in one shot.

 

[robm]

Arghhhhhh !

I hear you.

These last pictures are a horror story with nut tightened against FG with washers only for backing. These are more difficult to back up but it must be done.

Which ones? The pedestal mount bolts? The rudder mount bolts? If the latter, I have one update that makes me feel better: The rudder mount bolts appear to pass through an aluminum backing plate. I'm ~90% confident about this since I couldn't reach the plate for a scratch / poke test yesterday when taking the attached photo.

 

[robm]

Don’t do anything till we talk. What is your phone number. Hunter warranty called me for advice and had me involved on the east coast from Georgia to New York when others did not know how to repair.

Will PM you my contact info per your request, and thanks for being willing to provide your expert advice; much appreciated. Definitely won't be doing any work until after we chat. The only time pressure for the short term (say, Mon/Tue this week) would be for me to order backing plates, adhesive, and thickened epoxy to have on hand for a potential repair attempt next weekend. As with so many other things, supply chain issues seem to be affecting the availability of WS six10, JD TB Thixo, and other easy-to-use cartridge-based thickened epoxy options.

You have several things going on at one time.

Story of my life.

By the way at least one of the pedestal bolts are leaking.

You thinking port side aft? There's a bit of "not as clean" around that bolt. I reposted all of the photos with updated labels and numbering; see photo 012.

 

[Ralph Johnstone]

I'm ~90% confident about this since I couldn't reach the plate for a scratch / poke test yesterday when taking the attached photo.

Now somebody showed some respect for backing plates.

Could you please add a little detail to the above statement ? Not sure which side of the hull you were reaching from when you failed to reach the aluminum plate.

 

[robm]

Now somebody showed some respect for backing plates.

Could you please add a little detail to the above statement ? Not sure which side of the hull you were reaching from when you failed to reach the aluminum plate.

Interior. Didn’t have time to remove the batteries, so I wasn’t able to fit into the aft compartment. However, I was able to get a better angle for a photo that shows:

• The outline of a backing plate.
• Peeling paint / coating on the backing plate vs. delaminating fiberglass.
• Gray areas no longer covered by coating that look like aluminum.

 

[Ralph Johnstone]

After looking again and again at photos #8 and #10, I am convinced that your only problem shown in these pictures was due to towing the boat with the motor mounted on the transom as well as not being properly supported. You mentioned the weight of your engine somewhere back in these posts and I seem to remember it was no lightweight. I can imagine it created one hell of a static lifting force on those inner bolts when looking at pic #10 but add the bumping of going down a road and ouch, ouch, ouch !

I think if you vow never to tow the boat with the motor on the stern again, your problems will never occur again after you have repaired the existing damage.

1. Install sufficient backing plates of 1/4" aluminum with full contact backing as previously discussed. No need to go fancy with G10 unless you're fixated on it.

2. Grind out all of the structural damage to the FG shown in #1 and #2 and either soak with thinned epoxy if heavily damaged or just fill with gel coat if damage is light. Pure white gel coat should be a perfect match for your boat. It's a perfect match on my boat for all of the spider cracks I've patched over the years.

You'll want to do some inner soul searching before doing the repairs on the damaged motor supports. Do you want to open up the broken FG and fill with thinned epoxy and then quickly clamp the supports into place or is the damage not that severe ? I'm thinking about cracking your nice gel coat repair job several years down the road. I think you get my drift.

I think the rest of your gel cracks are simply due to age. I've got gel coat spider cracks in the most inexplainable locations you could imagine. No source of stress but there they are. Maybe they appear just to keep me occupied and away from the beer parlor.

 

[robm]

After looking again and again at photos #8 and #10, I am convinced that your only problem shown in these pictures was due to towing the boat with the motor mounted on the transom as well as not being properly supported. You mentioned the weight of your engine somewhere back in these posts and I seem to remember it was no lightweight. I can imagine it created one hell of a static lifting force on those inner bolts when looking at pic #10 but add the bumping of going down a road and ouch, ouch, ouch !

Agreed. I'm cringing just thinking about trailering AND leaving the motor in place 100% of the time without support until now. Never again!

Looking at this option re: motor support: Extreme Max 3001.1068 Adjustable Heavy-Duty Universal Transom Saver

I think if you vow never to tow the boat with the motor on the stern again, your problems will never occur again after you have repaired the existing damage.

Good advice. Would the motor support mentioned above suffice as an alternative to removing it for transport? I've already ordered one, and will use it for motor support during the season, regardless of the answer to this question.

1. Install sufficient backing plates of 1/4" aluminum with full contact backing as previously discussed. No need to go fancy with G10 unless you're fixated on it.

I have some aluminum bar stock on hand; I think I have 10 or 12 feet of 3"w x 1/4"d, and another 10 or 12 feet of something wider and thicker. I also have some stainless steel bar stock of similar dimensions, but that's overkill for this use case,

Am thinking that upgrading the existing pair of motor mount backing plates to 3"x12"x1/4" aluminum bar stock would be a significant upgrade that has the advantage of being easier to remove vs. larger G10 plates epoxied in place (if a future rebuild by a pro is warranted).

2. Grind out all of the structural damage to the FG shown in #1 and #2 and either soak with thinned epoxy if heavily damaged or just fill with gel coat if damage is light. Pure white gel coat should be a perfect match for your boat. It's a perfect match on my boat for all of the spider cracks I've patched over the years.

This sounds great. My concern in the short term re: this being a first time DIY gelcoat repair for me is that I imagine it would take a good amount of time to get it right.

Are there quicker options for a short-term fix that would get me to the end of the season (mid-Oct), but would not interfere with doing a proper fix as described above during the off-season? For example, this looks promising for sealing the cracks: Capt. Tolley's Creeping Crack Cure 2 oz.

However, I wouldn't want to use this quick fix if it would mess up doing a proper fix later this year.

You'll want to do some inner soul searching before doing the repairs on the damaged motor supports. Do you want to open up the broken FG and fill with thinned epoxy and then quickly clamp the supports into place or is the damage not that severe ? I'm thinking about cracking your nice gel coat repair job several years down the road. I think you get my drift.

Ideally, I'd rather do this properly the first time. BUT: If I can repair this in a manner that is quick and safe enough to finish out the season, and then potentially pay someone else to make the proper repairs, I would prefer this option.

I think the rest of your gel cracks are simply due to age. I've got gel coat spider cracks in the most inexplainable locations you could imagine. No source of stress but there they are. Maybe they appear just to keep me occupied and away from the beer parlor.

Concur on all points. The ones around the rudder mount "hump" look to be cosmetic age marks. I don't see any movement when I try to move the rudder mount bracket, and I confirmed that there's an aluminum backing plate for the through-bolts last Sunday.

I'm going to connect with @Crazy Dave Condon via phone this week. One or both of us can post a summary of our discussion so others can benefit from it.

Thanks again for your time and advice. Looking forward to choosing a solution, and getting moving on it this weekend.

Rob

 

[Ralph Johnstone]

Capt. Tolley's Creeping Crack Cure 2 oz.

Only from what I've seen here on SBO, the same cracks keep opening up again and again. It would likely screw up the chances of doing a permanent repair.

this being a first time DIY gelcoat repair for me is that I imagine it would take a good amount of time to get it right.

You require proof of a grade four reform school education to do a perfect SMALL gel coat repair. Lots of experience for a larger job. My boat is covered with small spider crack repairs which are invisible to the eye. I'm slower than the pros but get the same results. I'm also extremely lucky that pure white gel is a perfect colour match to my FG.

Looking at this option re: motor support: Extreme Max 3001.1068 Adjustable Heavy-Duty Universal Transom Saver

Like the manufacturer, I did the math but found that their support bar is not what they claim it to be. I hope the following will explain. No math, just vectors:

1. The weight of the OB engine pushes straight down.
2. The centre of mass of the engine overhangs the engine support by some distance.
3. The entire weight of the engine is supported upwards by the FG at the rear edge of the support platform. Bouncing down the road adds as much as 2-3g force to this small area.
4. This small supporting FG area acts as a fulcrum
4. The overhanging engine also causes a clockwise turning moment which lifts the damaged FG portion of the engine supports.

These forces are shown below:

If you take note of the support rod of the Extreme Max product, it can only offer a horizontal force as shown:

As the engine sits motionless, the bar will push aft to counter the clockwise turning moment caused by the weight of the motor. This will in turn eliminate the upward force on the damaged FG. The downward force due to the engine is not reduced by the support bar.

Unfortunately, this arrangement requires zero movement between all connecting parts or there will be lift on the damaged FG you now have. For this reason, the Extreme Max will offer next to no support to avoid damage to the inner support.

This is a common method of support in welded structures but again, these have no possibility of movement.

As far as current use of the boat, any way you can lash the motor to the interior of the boat while transporting it ?

 

[Sailavie1]

When I trailer my 2008 H25, I raise the motor up. I believe that this moves the motor center of balance foreword thus reducing the torque on the mounting bracket. I will start to strap the motor up to the transom railing to further reduce bounce (as suggested in this thread). So far my transom is showing no stress cracks and I trailer it 200 km. each year.

 

[Ralph Johnstone]

I believe that this moves the motor center of balance foreword thus reducing the torque on the mounting bracket.

The solution may be just as simple as that. If that 2g and 3g+ pounding is forcing straight down on the support platform, it would eliminate any upward forces. These upward forces are the only ones which fried @robm 's support platform.

Vastly superior to the Extreme Max bar and the price is right.

Never played with one of these before. Guess you had to be there to SEE what was happening.

Thanks @Sailavie1

 

[robm]

Only from what I've seen here on SBO, the same cracks keep opening up again and again. It would likely screw up the chances of doing a permanent repair.

Thanks. That’s good enough for me to pass on this option.

You require proof of a grade four reform school education to do a perfect SMALL gel coat repair. Lots of experience for a larger job. My boat is covered with small spider crack repairs which are invisible to the eye. I'm slower than the pros but get the same results. I'm also extremely lucky that pure white gel is a perfect colour match to my FG.

Noted and appreciated. Sounds like it’s worth giving it a shot after I fix the structural issues.

Like the manufacturer, I did the math but found that their support bar is not what they claim it to be. I hope the following will explain. No math, just vectors:

1. The weight of the OB engine pushes straight down.
2. The centre of mass of the engine overhangs the engine support by some distance.
3. The entire weight of the engine is supported upwards by the FG at the rear edge of the support platform. Bouncing down the road adds as much as 2-3g force to this small area.
4. This small supporting FG area acts as a fulcrum
4. The overhanging engine also causes a clockwise turning moment which lifts the damaged FG portion of the engine supports.

These forces are shown below:

View attachment 208878

Great job with the markup; makes it easy to follow. Your vectors confirm what I was thinking.

If you take note of the support rod of the Extreme Max product, it can only offer a horizontal force as shown:

View attachment 208875

As the engine sits motionless, the bar will push aft to counter the clockwise turning moment caused by the weight of the motor. This will in turn eliminate the upward force on the damaged FG. The downward force due to the engine is not reduced by the support bar.

Makes sense. However, if the extreme max support bar can be extended far enough, it would be able to support the motor in its tipped-forward position.

Unfortunately, this arrangement requires zero movement between all connecting parts or there will be lift on the damaged FG you now have. For this reason, the Extreme Max will offer next to no support to avoid damage to the inner support.

Agreed. I received the support bar today, so I will assemble it and see how much play there is. Assuming there is no play and that it is long enough to support the motor when tipped forward, this could end up being a viable option.

This is a common method of support in welded structures but again, these have no possibility of movement.

As far as current use of the boat, any way you can lash the motor to the interior of the boat while transporting it ?

Yes, I could lash the motor to a strong point while it is tipped up. However, I am leaning toward removing it for transport, because that feels like the safest option.

 

[Ralph Johnstone]

Yes, I could lash the motor to a strong point while it is tipped up. However, I am leaning toward removing it for transport, because that feels like the safest option.

That woulk

 

[Ralph Johnstone]

Makes sense. However, if the extreme max support bar can be extended far enough, it would be able to support the motor in its tipped-forward position.

You may be able to salvage some use out of the contraption for the final permanent solution.

Again, if this problem were mine I would be be completely satisfied with a permanent solution consisting of:

1. Installing improved backing plates behind the supports.
2. Grinding out the damage in the FG and refilling with whatever is required depending on the depth of damage. I would do it without the SS support in place to ensure no stresses added to the FG and no future cracking of the repaired gel coat.
3. Install the Extreme Max to allow travelling with the motor in the tipped forward position.
4. Doing cosmetic repairs on the other spider cracks when bored.

Post again once you start the permanent repairs this fall/winter either here or private message me. I'd really enjoy seeing how the repairs go.

 

[Crazy Dave Condon]

@robm and I spoke.

Discussed adding a quick disconnect for motor suggesting trollig motor plug. Suggested tying off motor to base of stern rail base or remove it. Suggested after ten miles to pull over checking tie downs and winch strap along with other issues to look for.

Suggested larger backing plates for motor and ladder. Suggested adding a long ss strap underneath the rear floor to strengthen that portion of the floor from flexing.

The gouge on port side of rudder on transom was hit by an object and could have caused some gel coat cracks but no fiberglass issues based on nothing seen.
Rudder base inside bolted on top of aluminum block but suggested use of larger washers.

As for gel coat there are no cracks in the diamond pattern of non skid. Suggested dremeling out down to fiberglass, filling with two part epoxy (Warer Tite which he has), and spray paint with Krylon plastic paint after matched by a color chart vs. gel coat as gel and plastic paints are petroleum based. Suggested taping off and shadowing the painting.

I did mention the motor when under power must be perpendicular to water line. I am familiar with the 9.8 hp Tohatsu motor as I was ax Tohatsu dealer.

I did request a photo of the Lewmar wheel steering. Not sure who installed wheel steering as it use to be Edson. I told robm for a year I dropped Hunter due to breach of contract until it was rectified and Warren Luhrs was.not happy a happy camper with sales.

Pointed out one wheel base bolt needed caulking due to discoloration of bolt head and water path on fiberglass beneath bolt.

Robm to fill in